METHOD FOR MANUFACTURING ENGINE CONTROL DEVICE, ENGINE SYSTEM, AND METHOD FOR CONTROLLING ENGINE SYSTEM

Abstract

To improve performance aggravation of an engine, due to fluctuation of compression ratios of the engine, as needed.SOLUTION: A manufacturing method of an ECU controlling an engine mounted with a plurality of cylinders comprises the steps of: identifying compression ratios of respective cylinders (S11 and S12); calculating maximum inner cylinder pressure of respective cylinders using the compression ratios (S13); calculating margins which are differences between the largest maximum inner cylinder pressure and the maximum inner cylinder pressure of respective cylinders (S14); identifying offset amounts with which injection timings indicated in a normal control map of fuel injection timings are advanced so as to increase inner cylinder pressures of respective cylinders by the margins (S15); and causing a memory of the ECU to store a program which controls the injection timings in a manner that advances the injection timings indicated in the normal control map by the offset amounts to prevent the offset amounts to advance ignition timings when an engine load is large from getting smaller than the same when the engine load is small (S16).SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a manufacturing method for an engine control device, an engine system, and a control method for an engine system, and in particular to a manufacturing method for an engine control device that controls a diesel engine having multiple cylinders, an engine system that includes a diesel engine having multiple cylinders and a control device that has a control unit and a memory unit and controls the diesel engine, and a control method for the engine system. [Background technology]

[0002] Conventionally, when the compression ratio varies among the cylinders of a multi-cylinder engine, there has been a control method for individually correcting the control conditions of the engine according to factors that determine the compression ratio of each cylinder (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-303191 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the method of Patent Document 1, the engine control conditions are individually corrected in all control ranges, which causes a problem that unnecessary control is performed in control ranges where the influence of the individual corrections is small.

[0005] This disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a method for manufacturing an engine control device, an engine system, and a method for controlling an engine system, which are capable of improving performance deterioration caused by variations in the compression ratio of the engine as needed. [Means for solving the problem]

[0006] The manufacturing method of an engine control device according to the present disclosure is a manufacturing method of an engine control device for controlling a diesel engine having a plurality of cylinders. The engine control device includes a storage unit. The manufacturing method includes the steps of: identifying a compression ratio of each cylinder of the diesel engine; calculating a maximum in-cylinder pressure of each cylinder using the identified compression ratio; calculating a margin between the largest of the calculated maximum in-cylinder pressures and the maximum in-cylinder pressure of each cylinder; identifying an offset amount for advancing the injection timing indicated in a normal control map of the fuel injection timing in order to increase the in-cylinder pressure of each cylinder by the calculated margin; and storing in the storage unit a program for controlling the injection timing indicated in the normal control map to be advanced by the identified offset amount so that the offset amount to be advanced is not reduced when the load on the diesel engine is large compared to when the load is small.

[0007] Preferably, the program controls the injection timing indicated by the normal control map to be advanced by a specified offset amount when a load of the diesel engine is equal to or greater than a specified load, and more preferably, the specified load is determined in advance based on an effect on noise generated by the diesel engine when the injection timing is advanced by the offset amount.

[0008] Preferably, the program controls the injection timing indicated by the normal control map so as to advance the injection timing by gradually increasing the reflection rate of the offset amount in accordance with the load of the diesel engine.

[0009] Preferably, the program controls the injection timing indicated by the normal control map so as to advance the injection timing by increasing the reflection rate of the offset amount monotonically in response to the load of the diesel engine.

[0010] According to another aspect of the disclosure, an engine system includes a diesel engine having a plurality of cylinders, and a control device including a control unit and a storage unit for controlling the diesel engine. The storage unit prestores a program for controlling the injection timing indicated in a normal control map of the fuel injection timing to be advanced by an offset amount so that the offset amount to be advanced does not become small when the load of the diesel engine is large compared to when it is small. The offset amount is an amount by which the injection timing indicated in the normal control map is advanced in order to increase the in-cylinder pressure of each cylinder by an allowance for each cylinder. The allowance is a difference between the largest of the maximum in-cylinder pressures of each cylinder and the maximum in-cylinder pressure of each cylinder. The maximum in-cylinder pressure is calculated using the compression ratio of each cylinder. The compression ratio is specified for each cylinder. The control unit determines whether the load of the diesel engine is large compared to when it is small according to the program stored in the storage unit, and when it determines that the load of the diesel engine is large compared to when it is small, controls the injection timing indicated in the normal control map to be advanced by an offset amount so that the offset amount does not become small.

[0011] According to yet another aspect of the disclosure, a method for controlling an engine system includes a diesel engine having a plurality of cylinders, and a control device having a control unit and a storage unit and controlling the diesel engine. The storage unit prestores a program for controlling the injection timing indicated in a normal control map of the fuel injection timing to be advanced by an offset amount so that the offset amount to be advanced is not reduced when the load of the diesel engine is large compared to when the load is small. The offset amount is an amount by which the injection timing indicated in the normal control map is advanced in order to increase the in-cylinder pressure of each cylinder by the margin of each cylinder. The margin is a difference between the largest of the maximum in-cylinder pressures of each cylinder and the maximum in-cylinder pressure of each cylinder. The maximum in-cylinder pressure is calculated using the compression ratio of each cylinder. The compression ratio is specified for each cylinder. The control method includes a step of the control unit determining whether the load on the diesel engine is large compared to when it is small according to a program stored in the memory unit, and a step of controlling, when the control unit determines that the load on the diesel engine is large compared to when it is small, to advance the injection timing indicated in the normal control map by the offset amount so that the offset amount does not become small. Effect of the Invention

[0012] According to this disclosure, when the load on the diesel engine is large compared to when the load is small, the injection timing shown in the normal control map is advanced by a specified offset amount so that the offset amount to be advanced is not small, and the maximum in-cylinder pressure of the advanced cylinder is increased by the difference between the maximum in-cylinder pressure of each cylinder and the injection timing shown in the normal control map by a specified offset amount. As a result, it is possible to provide a manufacturing method for an engine control device, an engine system, and a control method for an engine system, which are capable of improving performance deterioration caused by variations in the compression ratio of diesel engines as needed. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram showing a schematic configuration of an engine equipped with a cooling device according to an embodiment of the present invention; [Diagram 2] 4 is a flowchart showing an outline of a method for producing a part of a program for controlling the engine in this embodiment. [Diagram 3] 5A and 5B are diagrams for explaining the amount of protrusion of a piston in this embodiment. [Figure 4] 4 is a graph showing an example of an actual value of a compression ratio in this embodiment. [Diagram 5] 4 is a graph showing an example of an actual value of a maximum in-cylinder pressure in this embodiment. [Figure 6] 4 is a graph showing the relationship between fuel injection timing and in-cylinder pressure of the engine in this embodiment. [Figure 7] 4 is a graph showing the relationship between fuel injection timing and output of the engine in this embodiment. [Figure 8] 4 is a graph for explaining engine control by an ECU manufactured in this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[0015] Fig. 1 is a diagram showing a schematic configuration of an engine 1 equipped with a cooling device according to this embodiment. Although Fig. 1 shows a schematic cross section of one cylinder as a representative example, the engine 1 of this embodiment is equipped with a plurality of cylinders, and is specifically an in-line six-cylinder engine. Furthermore, the engine 1 is a diesel engine.

[0016] The engine 1 includes a cylinder head 2 and a cylinder block 3. An injector (fuel injection valve) 5 that injects fuel into a combustion chamber 4 is provided in a portion of the cylinder head 2 that corresponds to each cylinder. The injector 5 is connected to a common rail (not shown), and high-pressure fuel stored in the common rail is constantly supplied to the injector 5.

[0017] An intake passage for drawing air into the combustion chamber 4 is connected to the cylinder head 2 via an intake manifold 8. In addition, an exhaust passage for discharging exhaust gas after combustion is connected to the cylinder head 2 via an exhaust manifold 10. An intake valve 11 opens and closes between the combustion chamber 4 and the intake manifold 8. An exhaust valve 12 opens and closes between the combustion chamber 4 and the exhaust manifold 10.

[0018] A piston 26 is accommodated inside the cylinder block 3 so as to be able to reciprocate. The piston 26 is connected to a crankshaft 27 via a connecting rod 28. A head gasket 6 is sandwiched between the cylinder block 3 and the cylinder head 2 when the two are assembled. The thickness of the head gasket 6 is determined so that the upper end of the piston 26 (the part closest to the cylinder head 2) does not come into contact with the lower surface of the cylinder head 2 (the surface closer to the cylinder block 3) at top dead center, where the piston 26 is located at the top of its stroke (the position closest to the cylinder head 2 and the position farthest from the crankshaft 27) when the engine 1 is assembled.

[0019] The engine 1 further includes an electronic control unit (ECU) 40. The ECU 40 includes a memory 42 that stores a predetermined program and predetermined data, and a CPU (Central Processing Unit) 41 that executes the predetermined program stored in the memory 42 and controls the engine 1. The ECU 40 is provided with an accelerator opening Acc, an engine rotation speed Ne, and the like from various sensors.

[0020] The ECU 40 acquires the accelerator opening Acc and the engine rotation speed Ne, performs a predetermined process, and controls the injector 5 to control the injection of fuel into the combustion chamber 4.

[0021] In the above-described configuration, when there is variation in the compression ratio for each cylinder of the engine 1, if the control conditions of the engine 1 are individually corrected in accordance with the factors that determine the compression ratio for each cylinder, if the control conditions of the engine 1 are individually corrected in all control ranges, unnecessary control will be performed in control ranges that are less affected by the individual corrections.

[0022] Therefore, the manufacturing method of the ECU 40 is a manufacturing method of a control device that controls the engine 1 having a plurality of cylinders. The ECU 40 includes a storage unit. The manufacturing method includes a step of specifying a compression ratio of each cylinder of the diesel engine, a step of calculating a maximum in-cylinder pressure of each cylinder using the specified compression ratio, a step of calculating a margin that is a difference between the largest of the calculated maximum in-cylinder pressures and the maximum in-cylinder pressure of each cylinder, a step of specifying an offset amount for advancing the injection timing indicated in a normal control map of the fuel injection timing in order to increase the in-cylinder pressure of each cylinder by the calculated margin, and a step of storing a program in the storage unit that controls the injection timing indicated in the normal control map to be advanced by the specified offset amount so that the offset amount to be advanced does not become small when the load of the diesel engine is large compared to when the load is small.

[0023] In this way, when the load on the engine 1 is large compared to when the load is small, the injection timing shown in the normal control map is advanced by the specified offset amount so that the offset amount to be advanced is not small, and the maximum in-cylinder pressure of the advanced cylinder is increased by the difference with the maximum of the maximum in-cylinder pressures of the cylinders. As a result, the deterioration of performance caused by the variation in the compression ratio of the engine 1 can be improved as necessary.

[0024] Fig. 2 is a flowchart showing an outline of a method for manufacturing a part of a program for controlling engine 1 in this embodiment. Referring to Fig. 2, in manufacturing engine 1, the manufacturer measures the amount of protrusion h of piston 26 from cylinder block 3 when assembling piston 26 into each cylinder of cylinder block 3 (step S11).

[0025] Fig. 3 is a diagram for explaining the protrusion amount of piston 26 in this embodiment. With reference to Fig. 3, protrusion amount h of piston 26 is the length that the upper end of piston 26 protrudes from the upper surface of cylinder block 3 at the top dead center.

[0026] This protrusion amount h may be a different value for each cylinder because the dimensions of the piston 26, the connecting rod 28, and the crankshaft 27 vary within the tolerance range for each cylinder. This protrusion amount is measured in step S11.

[0027] Returning to FIG. 2, the manufacturer calculates the compression ratio of each cylinder using the projection amount h measured in step S11 (step S12). The compression ratio is a value obtained by dividing the volume of the combustion chamber 4 when it is at its largest by the volume when it is at its smallest. The volume of the piston recess is also included in the volume of the combustion chamber 4. The thickness of the head gasket 6 sandwiched between the cylinder head 2 and the cylinder block 3 is also taken into consideration when calculating the compression ratio.

[0028] Fig. 4 is a graph showing an example of an actual value of the compression ratio in this embodiment. Referring to Fig. 4, the design value (standard value) of the compression ratio of engine 1 in this embodiment is a value calculated from the dimensions of each part on the design drawing. Here, the design value of the compression ratio is the value shown by the leftmost bar graph of STD and the thick dashed line between the thin solid line indicating a compression ratio of 15.3 and the thin solid line indicating a compression ratio of 15.4.

[0029] The design upper limit of the compression ratio of the engine 1 is a value calculated from the maximum or minimum value of the dimensional tolerances of each component on the design drawings. Here, the design upper limit is the value indicated by the thick solid line between the thin solid line indicating a compression ratio of 15.5 and the thin solid line indicating a compression ratio of 15.6.

[0030] The design upper limit of the compression ratio of engine 1 is a value calculated from the maximum or minimum value of the dimensional tolerances of each part on the design drawings. Here, the design upper limit is the value indicated by the thick solid line that almost overlaps with the line indicating the compression ratio of 15.2.

[0031] The compression ratio values ​​calculated in step S12 for each of cylinders #1 through #6 are the values ​​shown in the bar graphs #1 through #6 to the right of the STD bar graph in Fig. 4. Here, the compression ratio of cylinder #1 is the maximum value among all the compression ratios of cylinders #1 through #6. This maximum value is shown by a thin dashed line that almost overlaps with the line indicating a compression ratio of 15.5.

[0032] Returning to FIG. 2, the manufacturer calculates the maximum in-cylinder pressure of each cylinder from the compression ratio of each cylinder calculated in step S12 (step S13). If the operating conditions of engine 1 other than the compression ratio are the same, the maximum in-cylinder pressure increases almost proportionally as the compression ratio increases. The relationship between various compression ratio values ​​and maximum in-cylinder pressure when engine 1 is operated under the highest load is specified in advance by simulation or actual measurement at the design stage. Using this relationship, the maximum in-cylinder pressure is calculated for each cylinder from the compression ratio.

[0033] Fig. 5 is a graph showing an example of the actual value of the maximum in-cylinder pressure in this embodiment. Referring to Fig. 5, the design value of the maximum in-cylinder pressure is a value specified from the design values ​​of the dimensions of each part and the design value of the compression ratio. Here, the design value of the maximum in-cylinder pressure is a value indicated by a thick dashed line between a thin solid line indicating a maximum in-cylinder pressure of 15.5 (MPa) and a thin solid line indicating a maximum in-cylinder pressure of 16.0.

[0034] The design upper limit of the maximum in-cylinder pressure is a value determined from the maximum or minimum tolerance of the dimensions on the design drawings of each component and the design upper or lower limit of the compression ratio. Here, the design upper limit of the maximum in-cylinder pressure is the value indicated by the thick solid line between the thin solid line indicating the maximum in-cylinder pressure of 16.0 (MPa) and the thin solid line indicating the maximum in-cylinder pressure of 16.5.

[0035] The maximum in-cylinder pressure values ​​calculated in step S13 for each of cylinders 1 to 6 are the values ​​indicated by bar graphs #1 to #6 in Fig. 5. Here, the maximum in-cylinder pressure of cylinder 1 is the maximum value among the maximum in-cylinder pressures of all cylinders 1 to 6. This maximum value is the value indicated by the thin dashed line between the thin solid line indicating the maximum in-cylinder pressure of 16.0 (MPa) and the thin solid line indicating the maximum in-cylinder pressure of 16.5 (MPa).

[0036] Returning to FIG. 2, the manufacturer calculates a margin of the maximum in-cylinder pressure of each cylinder from the maximum in-cylinder pressure calculated in step S13 (step S14).

[0037] Referring again to FIG. 5, since the maximum in-cylinder pressure of the first cylinder is the maximum value here, a margin is calculated which is the difference between the maximum in-cylinder pressure of the first cylinder and the maximum in-cylinder pressure of each cylinder.

[0038] Returning to FIG. 2, the manufacturer calculates, for each engine speed Ne, an offset amount of the advance angle that can use up the margin calculated in step S14 (step S15).

[0039] Fig. 6 is a graph showing the relationship between the fuel injection timing and the in-cylinder pressure of the engine 1 in this embodiment. Referring to Fig. 6, this graph is for a certain engine speed Ne. The injection timing is indicated by an angle after top dead center (called ATDC (After Top Dead Center)). If the ATDC angle is a negative value, the absolute value of this angle indicates an angle "before" the top dead center.

[0040] As shown in the graph of FIG. 6, the smaller the ATDC angle indicating the injection timing, that is, the more the injection timing is advanced (the greater the offset of the injection timing advance), the higher the in-cylinder pressure. A similar tendency is observed at other engine speeds Ne. This graph makes it possible to identify the angle by which the injection timing is advanced to increase the maximum in-cylinder pressure by an allowance at a certain engine speed Ne. In this way, the angle by which the injection timing is advanced is identified for each engine speed at a predetermined speed interval (for example, 100 rpm interval).

[0041] Fig. 7 is a graph showing the relationship between the fuel injection timing and the output of engine 1 in this embodiment. Referring to Fig. 7, for a certain cylinder, the smaller the ATDC angle indicating the injection timing, that is, the more the injection timing is advanced (the greater the offset amount of the advance of the injection timing), the greater the output of that cylinder. Therefore, if the maximum in-cylinder pressure for a certain cylinder is increased by an allowance, the output of that cylinder also increases.

[0042] Returning to Fig. 2, the manufacturer creates a program that adds an offset amount for advancing the injection timing shown in the normal control map (turns on the offset amount addition control) when the engine 1 is used at a load equal to or greater than the load specified, and does not add the offset amount (turns off the offset amount addition control) otherwise (when the engine 1 is used at a load less than the load specified), and stores the created program in the memory 42 of the ECU 40 of the engine 1. The normal control map for injection timing is a control map for injection timing that is normally used for the engine 1, and is a control map for a state in which the offset amount addition control in this embodiment is not performed.

[0043] Fig. 8 is a graph for explaining the control of engine 1 by ECU 40 manufactured in this embodiment. Referring to Fig. 8, when engine 1 with this program incorporated in ECU 40 is operated, if the load of engine 1 exceeds a designated load at time t, ECU 40 turns on the offset amount addition control for each cylinder in accordance with this program. As a result, the maximum in-cylinder pressure of each cylinder increases by an amount corresponding to the margin, and the output of that cylinder increases, so that the output of engine 1 increases.

[0044] The specified load is determined in advance based on the effect on noise generated by the engine 1 when the injection timing is advanced by the offset amount. For example, when the injection timing is advanced by the offset amount in a state in which the noise level does not exceed a predetermined tolerance, the specified load is the boundary load between the load at which the noise level does not exceed the predetermined tolerance and the load at which the noise level exceeds the predetermined tolerance.

[0045] [Variations] (1) In the above-described embodiment, as shown in step S16 of Fig. 2 and Fig. 8, the created program is a program that controls the injection timing shown in the normal control map to be advanced by an offset amount when the load of the engine 1 is equal to or greater than a specified load. In other words, the created program is a program that controls the injection timing to be advanced by 100% of the offset amount when the load of the engine 1 is equal to or greater than 90% of the maximum load, for example.

[0046] However, the present invention is not limited thereto, and the created program may be any program that controls the injection timing indicated by the normal control map to be advanced so that the offset amount to be advanced is not reduced when the load on the engine 1 is large compared to when the load on the engine 1 is small. For example, the created program may be a program that controls the control timing indicated by the normal control map to be advanced by gradually increasing the reflection ratio of the offset amount according to the load on the engine 1. In other words, the created program may be a program that controls the injection timing to be advanced by 30% of the offset amount when the load on the engine 1 is 50% or more of the maximum load, controls the injection timing to be advanced by 60% of the offset amount when the load on the engine 1 is 75% or more of the maximum load, and controls the injection timing to be advanced by 100% of the offset amount when the load on the engine 1 is 100% or more of the maximum load.

[0047] The created program may also be a program that controls the injection timing indicated in the normal control map to be advanced by increasing the reflection ratio of the offset amount in a monotonically increasing manner according to the load of the engine 1. In other words, the created program may be a program that controls the injection timing to be advanced by 100-x(%) of the offset amount when the load of the engine 1 is x% of the maximum load, for example.

[0048] (2) In the above-described embodiment, as shown in step S16 of Fig. 2 and Fig. 8, the specified load is a border load between a load where the noise level does not exceed a predetermined tolerance value and a load where the noise level exceeds a predetermined tolerance value when the injection timing is advanced by the offset amount in a state where the noise level does not exceed a predetermined tolerance value. However, the present invention is not limited to this, and the specified load may be a border load between a load where a person feels that the noise level is louder than before the injection timing is advanced by the offset amount and a load where a person does not feel that the noise level is louder than before the injection timing is advanced.

[0049] (3) Although the above-described embodiment does not specifically mention multi-stage injection, all of the stages of a multi-stage injection may be advanced by the same offset amount, or at least one of the stages of a multi-stage injection including the first stage injection (e.g., pilot injection) may be advanced by an offset amount, or when multiple stages of a multi-stage injection are advanced, they may be advanced by different offset amounts.

[0050] (4) The above disclosure can be understood as disclosure of a method for manufacturing an engine control device such as the ECU 40 of the engine 1 or a program executed by this control device. It can be understood as disclosure of the engine 1, a control device such as the ECU 40 of the engine 1, and an engine system including the engine 1 and the ECU 40. It can be understood as disclosure of a method for controlling the engine 1 by a control device such as the ECU 40 of the engine 1.

[0051] [summary] (1) As shown in Fig. 2, the manufacturing method of the ECU 40 is a manufacturing method of the ECU 40 that controls the engine 1, which is a diesel engine having a plurality of cylinders. The ECU 40 includes a memory 42. The manufacturing method includes the steps of: identifying a compression ratio of each cylinder of the engine 1 (for example, steps S11 and S12); calculating a maximum in-cylinder pressure of each cylinder using the identified compression ratio (for example, step S13); calculating a margin that is a difference between the largest of the calculated maximum in-cylinder pressures and the maximum in-cylinder pressure of each cylinder (for example, step S14); identifying an offset amount for advancing the injection timing indicated in a normal control map of the fuel injection timing in order to increase the in-cylinder pressure of each cylinder by the calculated margin (for example, step S15); and storing in the memory 42 a program for controlling the injection timing indicated in the normal control map to be advanced by the identified offset amount so that the offset amount to be advanced is not reduced when the load of the engine 1 is large compared to when the load is small (for example, step S16).

[0052] As a result, when the load of the engine 1 is large compared to when it is small, the injection timing indicated by the normal control map is advanced by the specified offset amount so that the offset amount to be advanced is not reduced, and the maximum in-cylinder pressure of the advanced cylinder is increased by the difference with the maximum in-cylinder pressure of each cylinder. As a result, the deterioration of performance caused by the variation in the compression ratio of the engine 1 can be improved as necessary. Specifically, the output of the engine 1 can be increased when the load of the engine 1 is large compared to when it is small.

[0053] (2) As shown in step S16 of FIG. 2 and in FIG. 8, the program stored in the memory 42 is a program for controlling the injection timing indicated in the normal control map to be advanced by the calculated offset amount when the load on the engine 1 is equal to or greater than a specified load.

[0054] As a result, when the load of the engine 1 is equal to or greater than the designated load, the injection timing indicated by the normal control map is advanced by the calculated offset amount, and the maximum cylinder pressure of the advanced cylinder is increased by the difference between the maximum cylinder pressure of each cylinder and the maximum cylinder pressure of the other cylinders. As a result, the deterioration of performance caused by the variation in the compression ratio of the engine 1 can be improved as necessary. Specifically, when the load of the engine 1 is equal to or greater than the designated load, the output of the engine 1 can be increased compared to when the injection timing is not advanced.

[0055] (3) As shown in step S16 of FIG. 2 and in FIG. 8, the specified load is determined in advance based on the effect on noise generated by the engine 1 when the injection timing is advanced by the offset amount.

[0056] This allows the load to be specified taking into account noise-related effects, thereby reducing adverse noise-related effects.

[0057] (4) As shown in the modified example described above, the program stored in memory 42 may be a program that controls the injection timing indicated by the normal control map to be advanced by gradually increasing the reflection rate of the offset amount in accordance with the load on engine 1.

[0058] As a result, the injection timing shown in the normal control map is advanced with the offset amount reflected in a stepwise manner according to the load of the engine 1, and the maximum cylinder pressure of the advanced cylinder is increased up to the difference with the largest of the maximum cylinder pressures of the cylinders. As a result, the deterioration of performance caused by the variation in the compression ratio of the engine 1 can be improved as necessary. Specifically, the output of the engine 1 can be increased in a stepwise manner according to the load of the engine 1.

[0059] (5) As shown in the modified example described above, the program stored in memory 42 may be a program that controls the injection timing indicated by the normal control map to be advanced by increasing the reflection rate of the offset amount monotonically according to the load on engine 1.

[0060] As a result, the injection timing shown in the normal control map is advanced with the reflection ratio of the offset amount increased in a monotonically increasing manner according to the load of the engine 1, and the maximum in-cylinder pressure of the advanced cylinder is increased up to the difference with the largest of the maximum in-cylinder pressures of the cylinders. As a result, the deterioration of performance caused by the variation in the compression ratio of the engine 1 can be improved as necessary. Specifically, the output of the engine 1 can be increased in a monotonically increasing manner according to the load of the engine 1.

[0061] (6) As shown in FIG. 1, the engine system includes an engine 1 having a plurality of cylinders, and an ECU 40 having a CPU 41 and a memory 42 and controlling the engine 1. As shown in step S16 of FIG. 2, the memory 42 stores in advance a program for controlling the injection timing indicated by the normal control map of the fuel injection timing to be advanced by an offset amount so that the offset amount to be advanced is not small when the load of the engine 1 is large compared to when the load is small. As shown in step S15 of FIG. 2, the offset amount is an amount by which the injection timing indicated by the normal control map is advanced in order to increase the in-cylinder pressure of each cylinder by the margin of each cylinder. As shown in step S14 of FIG. 2, the margin is the difference between the largest of the maximum in-cylinder pressures of each cylinder and the maximum in-cylinder pressure of each cylinder. As shown in step S13 of FIG. 2, the maximum in-cylinder pressure is calculated using the compression ratio of each cylinder. As shown in steps S11 and S12 of FIG. 2, the compression ratio is specified for each cylinder. As shown in step S16 of FIG. 2 and FIG. 8, the CPU 41 determines whether the load on the engine 1 is large compared to when it is small, according to the program stored in the memory 42, and when it determines that the load on the engine 1 is large compared to when it is small, controls the injection timing shown in the normal control map to be advanced by the offset amount so that the offset amount does not become small.

[0062] As a result, when the load of the engine 1 is large compared to when it is small, the injection timing indicated by the normal control map is advanced by the specified offset amount so that the offset amount to be advanced is not reduced, and the maximum in-cylinder pressure of the advanced cylinder is increased by the difference with the maximum in-cylinder pressure of each cylinder. As a result, the deterioration of performance caused by the variation in the compression ratio of the engine 1 can be improved as necessary. Specifically, the output of the engine 1 can be increased when the load of the engine 1 is large compared to when it is small.

[0063] (7) As shown in FIG. 1, the control method of the engine system includes an engine 1 having a plurality of cylinders, and an ECU 40 having a CPU 41 and a memory 42 and controlling the engine 1. As shown in step S16 of FIG. 2, the memory 42 stores in advance a program for controlling the injection timing indicated by the normal control map of the fuel injection timing to be advanced by an offset amount so that the offset amount to be advanced is not small when the load of the engine 1 is large compared to when the load is small. As shown in step S15 of FIG. 2, the offset amount is an amount by which the injection timing indicated by the normal control map is advanced in order to increase the in-cylinder pressure of each cylinder by the margin of each cylinder. As shown in step S14 of FIG. 2, the margin is the difference between the largest of the maximum in-cylinder pressures of each cylinder and the maximum in-cylinder pressure of each cylinder. As shown in step S13 of FIG. 2, the maximum in-cylinder pressure is calculated using the compression ratio of each cylinder. As shown in steps S11 and S12 of FIG. 2, the compression ratio is specified for each cylinder. As shown in step S16 of FIG. 2 and FIG. 8, the control method includes a step in which the CPU 41 determines whether the load on the engine 1 is large compared to when it is small, according to a program stored in the memory 42, and a step in which, when the CPU 41 determines that the load on the engine 1 is large compared to when it is small, the injection timing indicated in the normal control map is advanced by the offset amount so that the offset amount does not become small.

[0064] As a result, when the load of the engine 1 is large compared to when it is small, the injection timing indicated by the normal control map is advanced by the specified offset amount so that the offset amount to be advanced is not reduced, and the maximum in-cylinder pressure of the advanced cylinder is increased by the difference with the maximum in-cylinder pressure of each cylinder. As a result, the deterioration of performance caused by the variation in the compression ratio of the engine 1 can be improved as necessary. Specifically, the output of the engine 1 can be increased when the load of the engine 1 is large compared to when it is small.

[0065] It is also intended that the embodiments disclosed herein may be implemented in appropriate combination. The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is indicated by the claims, not by the description of the above-mentioned embodiments, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0066] 1 Engine, 2 Cylinder head, 3 Cylinder block, 4 Combustion chamber, 5 Injector, 6 Head gasket, 8 Intake manifold, 10 Exhaust manifold, 11 Intake valve, 12 Exhaust valve, 26 Piston, 27 Crankshaft, 28 Connecting rod, 40 ECU, 41 CPU, 42 Memory.

Claims

1. A method for manufacturing an engine control device for controlling a diesel engine having a plurality of cylinders, comprising: The engine control device includes a storage unit, The manufacturing method includes: determining a compression ratio for each cylinder of the diesel engine; calculating a maximum in-cylinder pressure of each cylinder using the identified compression ratio; calculating a margin which is a difference between the largest of the calculated maximum in-cylinder pressures and the maximum in-cylinder pressure of each cylinder; specifying an offset amount for advancing the injection timing shown in a normal control map of the fuel injection timing in order to increase the in-cylinder pressure of each cylinder by the calculated margin of each cylinder; and storing a program in the storage unit to control the injection timing indicated by the normal control map to be advanced by the specified offset amount so that the offset amount to be advanced does not become small when the load of the diesel engine is large compared to when the load is small, The method for manufacturing an engine control device, wherein the program controls the injection timing to be indicated by the normal control map when the load of the diesel engine is less than a predetermined load, and controls the injection timing to be advanced by the offset amount when the load of the diesel engine is equal to or greater than the predetermined load.

2. 2. The method for manufacturing an engine control device according to claim 1, wherein the predetermined load is determined in advance based on an effect on noise generated by the diesel engine when the injection timing is advanced by the offset amount.

3. 2. The method for manufacturing an engine control device according to claim 1, wherein the program controls the injection timing indicated by the normal control map to be advanced by gradually increasing a reflection rate of the offset amount according to a load on the diesel engine.

4. 2. The method for manufacturing an engine control device according to claim 1, wherein the program controls the injection timing indicated by the normal control map to be advanced by increasing a reflection ratio of the offset amount monotonically in response to a load on the diesel engine.

5. A method for manufacturing an engine control device for controlling a diesel engine having multiple cylinders, comprising: The engine control device includes a storage unit, The manufacturing method includes: determining a compression ratio for each cylinder of the diesel engine; calculating a maximum in-cylinder pressure of each cylinder using the identified compression ratio; calculating a margin which is a difference between the largest of the calculated maximum in-cylinder pressures and the maximum in-cylinder pressure of each cylinder; specifying an offset amount for advancing the injection timing shown in a normal control map of the fuel injection timing in order to increase the in-cylinder pressure of each cylinder by the calculated margin of each cylinder; and storing a program in the storage unit to control the injection timing indicated by the normal control map to be advanced by the specified offset amount so that the offset amount to be advanced does not become small when the load of the diesel engine is large compared to when the load is small, The method for manufacturing an engine control device, wherein the program controls the injection timing indicated by the normal control map to be advanced by gradually increasing the reflection rate of the offset amount in accordance with the load of the diesel engine.

6. A method for manufacturing an engine control device for controlling a diesel engine having multiple cylinders, comprising: The engine control device includes a storage unit, The manufacturing method includes: determining a compression ratio for each cylinder of the diesel engine; calculating a maximum in-cylinder pressure of each cylinder using the identified compression ratio; calculating a margin which is a difference between the largest of the calculated maximum in-cylinder pressures and the maximum in-cylinder pressure of each cylinder; specifying an offset amount for advancing the injection timing shown in a normal control map of the fuel injection timing in order to increase the in-cylinder pressure of each cylinder by the calculated margin of each cylinder; and storing a program in the storage unit to control the injection timing indicated by the normal control map to be advanced by the specified offset amount so that the offset amount to be advanced does not become small when the load of the diesel engine is large compared to when the load is small, The manufacturing method of an engine control device, wherein the program controls the injection timing indicated by the normal control map to be advanced by increasing the reflection ratio of the offset amount monotonically in accordance with the load of the diesel engine.

7. An engine system including a diesel engine having a plurality of cylinders, and a control device having a control unit and a memory unit and controlling the diesel engine, the storage unit pre-stores a program for controlling the injection timing indicated by a normal control map of the fuel injection timing to be advanced by an offset amount so that the offset amount to be advanced does not become small when the load of the diesel engine is large compared to when the load is small, the offset amount is an amount by which the injection timing indicated in the normal control map is advanced in order to increase the in-cylinder pressure of each cylinder by an amount corresponding to a margin for each cylinder, the margin is a difference between the largest of the maximum in-cylinder pressures of each cylinder and the maximum in-cylinder pressure of each cylinder, The maximum in-cylinder pressure is calculated using a compression ratio of each cylinder, The compression ratio is specified for each cylinder, The control unit executes the program stored in the storage unit. determining whether a load on the diesel engine is large compared to when the load is small; When it is determined that the load of the diesel engine is large compared to when it is small, the injection timing indicated by the normal control map is advanced by the offset amount so that the offset amount does not become small; an engine system that controls the injection timing according to the normal control map when the load of the diesel engine is less than a predetermined load, and controls the injection timing according to the normal control map to be advanced by the offset amount when the load of the diesel engine is equal to or greater than the predetermined load.

8. A control method for an engine system including a diesel engine having a plurality of cylinders and a control device having a control unit and a memory unit and controlling the diesel engine, the storage unit pre-stores a program for controlling the injection timing indicated by a normal control map of the fuel injection timing to be advanced by an offset amount so that the offset amount to be advanced does not become small when the load of the diesel engine is large compared to when the load is small, the offset amount is an amount by which the injection timing indicated in the normal control map is advanced in order to increase the in-cylinder pressure of each cylinder by an amount corresponding to a margin for each cylinder, the margin is a difference between the largest of the maximum in-cylinder pressures of each cylinder and the maximum in-cylinder pressure of each cylinder, The maximum in-cylinder pressure is calculated using a compression ratio of each cylinder, The compression ratio is specified for each cylinder, The control method includes: a step of the control unit determining whether a load on the diesel engine is large compared to when the load is small; When the control unit determines that the load of the diesel engine is large compared to when the load is small, the control unit controls the injection timing indicated by the normal control map to be advanced by the offset amount so that the offset amount does not become small. and controlling the injection timing to be indicated by the normal control map when the load of the diesel engine is less than a predetermined load, while controlling the injection timing to be advanced by the offset amount when the load of the diesel engine is equal to or greater than the predetermined load.

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