Method and system for controlling marine propulsion device

Abstract

To improve accuracy of determining accidental fire in an engine, in a marine propulsion device comprising the engine with a plurality of cylinders.SOLUTION: A method according to the present invention is a method for controlling a marine propulsion device comprising an engine with a plurality of cylinders and a crankshaft. The method comprises: acquiring an angular acceleration of the crankshaft; acquiring a determination parameter for determining accidental fire in the engine based on an angular acceleration of the crankshaft; and determining the accidental fire in the engine by comparing the determination parameter with a threshold value set for each of the plurality of cylinders.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a method and a system for controlling a marine propeller.

Background Art

[0002] Some marine propellers are configured to determine misfires in an engine. For example, in the outboard motor disclosed in Patent Document 1, a controller acquires the angular acceleration of a crankshaft and the deviation of the angular acceleration. The controller determines whether the angular acceleration is less than a predetermined angular acceleration threshold value. Further, the controller determines whether the absolute value of the deviation of the angular acceleration is greater than a predetermined deviation threshold value. When the angular acceleration is less than the angular acceleration threshold value and the absolute value of the deviation of the angular acceleration is greater than the deviation threshold value, the controller determines that a misfire has occurred in the engine.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above outboard motor, misfires are determined for a plurality of cylinders of the engine using the same angular acceleration threshold value and the same deviation threshold value. However, since there are variations in the combustion state among the cylinders, an appropriate threshold value for accurately determining misfires is different for each cylinder. Therefore, when misfires are determined for a plurality of cylinders using the same angular acceleration threshold value and the same deviation threshold value as described above, it is not easy to improve the accuracy of misfire determination. An object of the present invention is to improve the accuracy of misfire determination in an engine in a marine propeller including a plurality of cylinders.

Means for Solving the Problems

[0005] A method according to an aspect of the present invention is a method for controlling a marine propeller equipped with an engine. The engine includes a plurality of cylinders and a crankshaft. The method includes obtaining an angular acceleration of the crankshaft, obtaining a determination parameter for determining an engine misfire based on the angular acceleration of the crankshaft, and determining an engine misfire by comparing the determination parameter with a threshold value set for each of the plurality of cylinders.

[0006] A system according to another aspect of the present invention is a system for controlling a marine propeller equipped with an engine. The engine includes a plurality of cylinders and a crankshaft. The system includes a sensor and a controller. The sensor detects an angular acceleration of the crankshaft. The controller obtains the angular acceleration of the crankshaft. The controller obtains a determination parameter for determining an engine misfire based on the angular acceleration of the crankshaft. The controller determines an engine misfire by comparing the determination parameter with a threshold value set for each of the plurality of cylinders.

Advantages of the Invention

[0007] In the present invention, an engine misfire is determined by comparing a determination parameter with a threshold value set for each of a plurality of cylinders. Therefore, even if there are variations in the combustion state among the cylinders, the misfire can be accurately determined by using the threshold values appropriately set for each cylinder.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0009] Hereinafter, a marine propeller according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing a marine propeller 1 according to the embodiment. The marine propeller 1 according to the present embodiment is an outboard motor. The marine propeller 1 includes a cowl 2, an upper housing 3, a lower housing 4, an engine 5, and a bracket 6. The upper housing 3 is disposed below the cowl 2. The lower housing 4 is disposed below the upper housing 3. The marine propeller 1 is attached to a ship (not shown) via the bracket 6. The engine 5 is disposed within the cowl 2. The engine 5 includes a crankshaft 11. The crankshaft 11 extends in the vertical direction.

[0010] The marine propeller 1 includes a drive shaft 12, a propeller shaft 13, and a shift mechanism 14. The drive shaft 12 is disposed within the upper housing 3 and the lower housing 4. The drive shaft 12 extends in the vertical direction. The upper end of the drive shaft 12 is connected to the lower end of the crankshaft 11.

[0011] A propeller 15 is disposed at the lower part of the lower housing 4. The propeller 15 is disposed below the engine 5. The propeller 15 is connected to the propeller shaft 13. The propeller shaft 13 extends in the front-rear direction. The propeller shaft 13 is connected to the drive shaft 12 via the shift mechanism 14. The shift mechanism 14 switches the rotational direction of the power transmitted from the drive shaft 12 to the propeller shaft 13. The shift mechanism 14 includes, for example, a plurality of gears and clutches. The propeller shaft 13 is rotationally driven by the driving force transmitted from the engine 5 via the drive shaft 12.

[0012] Figure 2 is a top view of the engine 5. Figure 3 is a schematic diagram showing the configuration of the control system of the engine 5 and the ship propeller 1. As shown in FIGS. 2 and 3, the engine 5 includes a first bank 21 and a second bank 22. As shown in FIG. 3, the first bank 21 includes a first cylinder C1, a third cylinder C3, and a fifth cylinder C5. The second bank 22 includes a second cylinder C2, a fourth cylinder C4, and a sixth cylinder C6. The second bank 22 is arranged side by side with the first bank 21 in a V shape. That is, the engine 5 is a V-type six-cylinder engine.

[0013] As shown in FIG. 2, the first cylinder C1 includes a combustion chamber 23A, an intake port 24A, and an exhaust port 25A. The intake port 24A and the exhaust port 25A are connected to the combustion chamber 23A. The first cylinder C1 includes an intake valve 26A and an intake cam 27A. The intake valve 26A opens and closes the intake port 24A. The intake cam 27A rotates by the driving force from the engine 5 to operate the intake valve 26A. The first cylinder C1 includes an exhaust valve 28A and an exhaust cam 29A. The exhaust valve 28A opens and closes the exhaust port 25A. The exhaust cam 29A rotates by the driving force from the engine 5 to operate the exhaust valve 28A.

[0014] The second cylinder C2 has a structure that is generally symmetrical to the left and right with the first cylinder C1. The second cylinder C2 includes a combustion chamber 23B, an intake port 24B, an exhaust port 25B, an intake valve 26B, an intake cam 27B, an exhaust valve 28B, and an exhaust cam 29B. The combustion chamber 23B, the intake port 24B, the exhaust port 25B, the intake valve 26B, the intake cam 27B, the exhaust valve 28B, and the exhaust cam 29B of the second cylinder C2 have the same configuration as the combustion chamber 23A, the intake port 24A, the exhaust port 25A, the intake valve 26A, the intake cam 27A, the exhaust valve 28A, and the exhaust cam 29A of the first cylinder C1, respectively.

[0015] The third cylinder C3 and the fifth cylinder C5 have the same structure as the first cylinder C1. The first cylinder C1, the third cylinder C3, and the fifth cylinder C5 are arranged side by side in the vertical direction. The fourth cylinder C4 and the sixth cylinder C6 have the same structure as the second cylinder C2. The second cylinder C2, the fourth cylinder C4, and the sixth cylinder C6 are arranged side by side in the vertical direction.

[0016] As shown in FIG. 3, the marine propeller 1 includes an intake pipe 31 and a throttle valve 32. The intake pipe 31 is connected to the intake ports of the respective cylinders C1 - C6. Through the intake pipe 31, the air-fuel mixture is sent to the intake ports of the respective cylinders C1 - C6. The throttle valve 32 is attached to the intake pipe 31. By changing the opening degree of the throttle valve 32, the amount of intake air sent to the combustion chambers of the respective cylinders C1 - C6 is adjusted.

[0017] The marine propeller 1 is provided with fuel injection devices 33A - 33F and ignition devices 34A - 34F. The fuel injection devices 33A - 33F and the ignition devices 34A - 34F are respectively attached to the respective cylinders C1 - C6. The fuel injection devices 33A - 33F inject fuel into the intake ports of the respective cylinders C1 - C6. The ignition devices 34A - 34F ignite the fuel in the combustion chambers of the respective cylinders C1 - C6.

[0018] The marine propeller 1 includes a first exhaust manifold 35, a second exhaust manifold 36, and an exhaust pipe 37. The first exhaust manifold 35 is connected to the exhaust ports of the cylinders C1, C3, C5 of the first bank 21. The second exhaust manifold 36 is connected to the exhaust ports of the cylinders C2, C4, C6 of the second bank 22.

[0019] The exhaust pipe 37 is connected to the first exhaust manifold 35 and the second exhaust manifold 36. A catalyst 38 is disposed in the exhaust pipe 37. The catalyst 38 is, for example, a three-way catalyst and purifies the exhaust passing through the exhaust pipe 37. The exhaust from the cylinders C1, C3, C5 of the first bank is discharged outside the marine propeller 1 through the first exhaust manifold 35 and the exhaust pipe 37. The exhaust from the cylinders C2, C4, C6 of the second bank is discharged outside the marine propeller 1 through the second exhaust manifold 36 and the exhaust pipe 37.

[0020] The marine propeller 1 includes a controller 40. The controller 40 is an electronic control unit and includes a processor such as a CPU and memories such as a RAM and a ROM. The controller 40 stores a program for controlling the engine 5 and executes processes for controlling the engine 5 according to the program. The controller 40 controls the throttle valve 32, the fuel injection devices 33A - 33F, and the ignition devices 34A - 34F based on data regarding the engine 5 detected by sensors described later.

[0021] The marine propeller 1 includes an intake pressure sensor 41 and an engine rotation sensor 42. The intake pressure sensor 41 is attached to the intake pipe 31 and detects the intake pressure in the intake pipe 31. The controller 40 detects the engine rotation speed, the angular velocity of the crankshaft 11, the angular acceleration, and the angular acceleration deviation by means of the engine rotation sensor 42. Specifically, the engine 5 includes a flywheel 43. The flywheel 43 is connected to the crankshaft 11 and includes a plurality of protrusions 44 arranged at intervals in the circumferential direction of the flywheel 43. In the drawings, only one of the plurality of protrusions is denoted by the reference numeral 44, and the reference numerals of the other protrusions are omitted.

[0022] The engine rotation sensor 42 is a magnetic sensor and detects the passage of each protrusion 44 of the flywheel 43. The controller 40 calculates the angular velocity of the crankshaft 11 based on the time interval of detection of each protrusion 44 and the angle between each protrusion 44. The controller 40 calculates the engine rotation speed based on the angular velocity of the crankshaft 11. Further, the controller 40 calculates the angular acceleration of the crankshaft 11 based on the angular velocity of the crankshaft 11.

[0023] The controller 40 executes misfire monitoring control for monitoring misfires in the engine 5 based on the data detected by the above-described sensors. Misfire means that fuel combustion does not occur in the combustion chamber of at least one of the plurality of cylinders C1 - C6 for some reason. Hereinafter, the misfire monitoring control will be described. FIGS. 4 and 5 are flowcharts showing the processing of the misfire monitoring control executed by the controller 40.

[0024] As shown in FIG. 4, in step S101, the controller 40 starts counting the number of ignition times n. The number of ignition times n is the total number of ignition times in the plurality of cylinders C1 - C6. In step S102, the controller 40 acquires the engine rotation speed. The controller 40 acquires the engine rotation speed based on the data from the engine rotation sensor 42. The controller 40 acquires the engine rotation speed at each ignition timing in the plurality of cylinders C1 - C6.

[0025] In step S103, the controller 40 acquires the angular acceleration α(n). The angular acceleration α(n) is a determination parameter for determining misfires in the engine 5. The controller 40 acquires the angular acceleration α(n) based on the data from the engine rotation sensor 42. The controller 40 acquires the angular acceleration α(n) at each ignition timing in the plurality of cylinders C1 - C6.

[0026] In step S104, the controller 40 acquires an angular acceleration deviation Δα(n). The angular acceleration deviation Δα(n) is a determination parameter for determining misfire of the engine 5. The controller 40 acquires the angular acceleration deviation Δα(n) based on the change in the angular acceleration α(n). The controller 40 acquires the angular acceleration deviation Δα(n) at the respective ignition timings in the plurality of cylinders C1 - C6.

[0027] In step S105, the controller 40 determines whether the angular acceleration α(n) is less than a predetermined angular acceleration threshold value αth. The angular acceleration threshold value αth is set individually for each of the plurality of cylinders C1 - C6. FIG. 6 is a diagram showing an example of threshold data D1 of the angular acceleration threshold value αth in each of the cylinders C1 - C6. The angular acceleration threshold value αth changes according to the engine rotational speed. The threshold data of the angular acceleration threshold value αth defines the relationship between the engine rotational speed and the angular acceleration threshold value αth. Note that the angular acceleration threshold value αth also changes according to the intake pressure. The controller 40 stores threshold data corresponding to the intake pressure. The threshold data D1 shown in FIG. 6 shows the relationship between the engine rotational speed and the angular acceleration threshold value αth at a predetermined intake pressure.

[0028] The threshold data D1 includes first threshold data D11, second threshold data D12, third threshold data D13, fourth threshold data D14, fifth threshold data D15, and sixth threshold data D16. The first threshold data D11 defines the relationship between the angular acceleration threshold αth (hereinafter referred to as the first threshold αth1) in the first cylinder C1 and the engine rotational speed. The second threshold data D12 defines the relationship between the angular acceleration threshold αth (hereinafter referred to as the second threshold αth2) in the second cylinder C2 and the engine rotational speed. The third threshold data D13 defines the relationship between the angular acceleration threshold αth (hereinafter referred to as the third threshold αth3) in the third cylinder C3 and the engine rotational speed. The fourth threshold data D14 defines the relationship between the angular acceleration threshold αth (hereinafter referred to as the fourth threshold αth4) in the fourth cylinder C4 and the engine rotational speed. The fifth threshold data D15 defines the relationship between the angular acceleration threshold αth (hereinafter referred to as the fifth threshold αth5) in the fifth cylinder C5 and the engine rotational speed. The sixth threshold data D16 defines the relationship between the angular acceleration threshold αth (hereinafter referred to as the sixth threshold αth6) in the sixth cylinder C6 and the engine rotational speed.

[0029] The first threshold data D11, the second threshold data D12, the third threshold data D13, the fourth threshold data D14, the fifth threshold data D15, and the sixth threshold data D16 exhibit different characteristics from each other. Therefore, the first to sixth thresholds αth1-αth6 for the same engine rotational speed are different from each other. However, a part of the first to sixth thresholds αth1-αth6 for the same engine rotational speed may be the same.

[0030] The controller 40 determines the first threshold αth1 from the engine rotational speed with reference to the first threshold data D11. The controller 40 determines the second threshold αth2 from the engine rotational speed with reference to the second threshold data D12. The controller 40 determines the third threshold αth3 from the engine rotational speed with reference to the third threshold data D13. The controller 40 determines the fourth threshold αth4 from the engine rotational speed with reference to the fourth threshold data D14. The controller 40 determines the fifth threshold αth5 from the engine rotational speed with reference to the fifth threshold data D15. The controller 40 determines the sixth threshold αth6 from the engine rotational speed with reference to the sixth threshold data D16.

[0031] In step S105, the controller 40 determines whether the angular acceleration α(n) at the ignition timing of the first cylinder C1 is less than the first threshold αth1. The controller 40 determines whether the angular acceleration α(n) at the ignition timing of the second cylinder C2 is less than the second threshold αth2. The controller 40 determines whether the angular acceleration α(n) at the ignition timing of the third cylinder C3 is less than the third threshold αth3. The controller 40 determines whether the angular acceleration α(n) at the ignition timing of the fourth cylinder C4 is less than the fourth threshold αth4. The controller 40 determines whether the angular acceleration α(n) at the ignition timing of the fifth cylinder C5 is less than the fifth threshold αth5. The controller 40 determines whether the angular acceleration α(n) at the ignition timing of the sixth cylinder C6 is less than the sixth threshold αth6. In step S105, when the angular acceleration α(n) at the ignition timing of any of the plurality of cylinders C1 - C6 is less than the angular acceleration thresholds αth1 - αth6 set for each of the cylinders C1 - C6, the process proceeds to step S106.

[0032] In step S106, the controller 40 determines whether the absolute value of the angular acceleration deviation Δα(n) is greater than a predetermined deviation threshold value Δαth_M. The deviation threshold value Δαth_M is individually set for each of the plurality of cylinders C1 - C6. FIG. 7 is a diagram showing an example of the threshold data D2 of the deviation threshold value Δαth_M in each of the cylinders C1 - C6. The deviation threshold value Δαth_M changes according to the engine rotational speed. The threshold data D2 of the deviation threshold value Δαth_M defines the relationship between the engine rotational speed and the deviation threshold value Δαth_M. Note that the deviation threshold value Δαth_M also changes according to the intake pressure. The controller 40 stores the threshold data corresponding to the intake pressure. The threshold data D2 shown in FIG. 7 shows the relationship between the engine rotational speed and the deviation threshold value Δαth_M at a predetermined intake pressure.

[0033] The threshold data D2 includes first threshold data D21, second threshold data D22, third threshold data D23, fourth threshold data D24, fifth threshold data D25, and sixth threshold data D26. The first threshold data D21 defines the relationship between the deviation threshold value Δαth_M (hereinafter referred to as the first deviation threshold value Δαth1) in the first cylinder C1 and the engine rotational speed. The second threshold data D22 defines the relationship between the deviation threshold value Δαth_M (hereinafter referred to as the second deviation threshold value Δαth2) in the second cylinder C2 and the engine rotational speed. The third threshold data D23 defines the relationship between the deviation threshold value Δαth_M (hereinafter referred to as the third deviation threshold value Δαth3) in the third cylinder C3 and the engine rotational speed. The fourth threshold data D24 defines the relationship between the deviation threshold value Δαth_M (hereinafter referred to as the fourth deviation threshold value Δαth4) in the fourth cylinder C4 and the engine rotational speed. The fifth threshold data D25 defines the relationship between the deviation threshold value Δαth_M (hereinafter referred to as the fifth deviation threshold value Δαth5) in the fifth cylinder C5 and the engine rotational speed. The sixth threshold data D26 defines the relationship between the deviation threshold value Δαth_M (hereinafter referred to as the sixth deviation threshold value Δαth6) in the sixth cylinder C6 and the engine rotational speed.

[0034] The first threshold data D21, the second threshold data D22, the third threshold data D23, the fourth threshold data D24, the fifth threshold data D25, and the sixth threshold data D26 exhibit different characteristics from each other. Therefore, the first to sixth deviation thresholds Δαth1 - Δαth6 for the same engine rotational speed are different from each other. However, some of the first to sixth deviation thresholds Δαth1 - Δαth6 for the same engine rotational speed may be the same.

[0035] The controller 40 determines the first deviation threshold Δαth1 from the engine rotational speed with reference to the first threshold data D21. The controller 40 determines the second deviation threshold Δαth2 from the engine rotational speed with reference to the second threshold data D22. The controller 40 determines the third deviation threshold Δαth3 from the engine rotational speed with reference to the third threshold data D23. The controller 40 determines the fourth deviation threshold Δαth4 from the engine rotational speed with reference to the fourth threshold data D24. The controller 40 determines the fifth deviation threshold Δαth5 from the engine rotational speed with reference to the fifth threshold data D25. The controller 40 determines the sixth deviation threshold Δαth6 from the engine rotational speed with reference to the sixth threshold data D26.

[0036] In step S106, the controller 40 determines whether the absolute value of the angular acceleration deviation Δα(n) at the ignition timing of the first cylinder C1 is greater than the first deviation threshold value Δαth1. The controller 40 determines whether the absolute value of the angular acceleration deviation Δα(n) at the ignition timing of the second cylinder C2 is greater than the second deviation threshold value Δαth2. The controller 40 determines whether the absolute value of the angular acceleration deviation Δα(n) at the ignition timing of the third cylinder C3 is greater than the third deviation threshold value Δαth3. The controller 40 determines whether the absolute value of the angular acceleration deviation Δα(n) at the ignition timing of the fourth cylinder C4 is greater than the fourth deviation threshold value Δαth4. The controller 40 determines whether the absolute value of the angular acceleration deviation Δα(n) at the ignition timing of the fifth cylinder C5 is greater than the fifth deviation threshold value Δαth5. The controller 40 determines whether the absolute value of the angular acceleration deviation Δα(n) at the ignition timing of the sixth cylinder C6 is greater than the sixth deviation threshold value Δαth6. When the absolute value of the angular acceleration deviation Δα(n) at the ignition timing of any one of the plurality of cylinders C1 - C6 is greater than the deviation threshold values Δαth1 - Δαth6 set for each of the cylinders C1 - C6, the process proceeds to step S107.

[0037] In step S107, the controller 40 determines whether the angular acceleration α(n + 1) is less than the angular acceleration threshold value αth. Similar to step S105, the controller 40 determines whether the angular acceleration α(n + 1) is less than the angular acceleration threshold value αth. When the angular acceleration α(n + 1) is less than the angular acceleration threshold value αth, the process proceeds to step S108.

[0038] In step S108, the controller 40 determines whether the absolute value of the angular acceleration deviation Δα(n + 2) is greater than a predetermined deviation threshold value Δαth_P. The deviation threshold value Δαth_P is the deviation threshold value when changing to the acceleration side at the time of the return of the angular acceleration deviation. The deviation threshold value Δαth_P is individually set for each of the plurality of cylinders C1 - C6, similar to the deviation threshold value Δαth_M.

[0039] Similar to step S106, the controller 40 determines whether the absolute value of the angular acceleration deviation Δα(n+2) corresponding to each of the cylinders C1-C6 is greater than the deviation threshold Δαth_P individually set for each of the cylinders C1-C6. When the absolute value of the angular acceleration deviation Δα(n+2) at the ignition timing of any of the plurality of cylinders C1-C6 is greater than the deviation threshold Δαth_P set for each of the cylinders C1-C6, the process proceeds to step S109. In step S109, the controller 40 adds 2 to the misfire count NL. That is, the controller 40 counts misfires in two consecutive cylinders.

[0040] In step S107, when the angular acceleration α(n+1) is equal to or greater than the angular acceleration threshold αth, the process proceeds to step S110. In step S110, the controller 40 determines whether the absolute value of the angular acceleration deviation Δα(n+1) is greater than a predetermined deviation threshold Δαth_P. When the absolute value of the angular acceleration deviation Δα(n+1) is greater than the predetermined deviation threshold Δαth_P, the process proceeds to step S111. In step S111, the controller 40 adds 1 to the misfire count NL. That is, the controller 40 counts misfires in a single cylinder.

[0041] As shown in FIG. 5, in step S112, the controller 40 calculates the misfire rate R. The controller 40 calculates the misfire rate R according to the following formula (1). R = NL / n ···(1) That is, the misfire rate is the ratio of the misfire count NL to the ignition count n. In step S113, the controller 40 determines whether the misfire rate R is equal to or greater than a predetermined misfire rate threshold Rth. When the misfire rate R is equal to or greater than the predetermined misfire rate threshold Rth, the process proceeds to step S114.

[0042] In step S114, the controller 40 outputs an alarm signal. As shown in FIG. 3, the control system of the marine propeller 1 includes an alarm device 45. The alarm device 45 notifies the user of the occurrence of a misfire in the engine 5. The alarm device 45 includes, for example, a display. The alarm device 45 is arranged on the ship on which the marine propeller 1 is mounted. Alternatively, the alarm device 45 may be provided on the marine propeller 1.

[0043] When the misfire rate R is equal to or higher than a predetermined misfire rate threshold Rth, the controller 40 determines that a misfire has occurred in the engine 5. When the controller 40 determines that a misfire has occurred in the engine 5, the controller 40 controls the alarm device 45 to notify the user of the occurrence of the misfire. For example, by outputting an alarm signal to the alarm device 45, the controller 40 causes the alarm device 45 to display the occurrence of the misfire by means of a message, an icon, or the like.

[0044] In step S115, the ignition count n is reset to 0. Also, in step S116, the misfire count NL is reset to 0. Then, the process returns to step S101, and the controller 40 repeatedly executes the processes from step S101 to step S116.

[0045] In the marine propeller 1 according to the present embodiment described above, by comparing the angular acceleration α(n) of the crankshaft 11 with the angular acceleration thresholds αth1-αth6 set for each of the plurality of cylinders C1-C6, misfires in the engine 5 are determined. Also, by comparing the angular acceleration deviation Δα(n) of the crankshaft 11 with the deviation thresholds Δαth1-Δαth6 set for each of the plurality of cylinders C1-C6, misfires in the engine 5 are determined. Therefore, even if there are variations in the combustion states among the plurality of cylinders C1-C6, misfires can be accurately determined by using the thresholds appropriately set for each of the cylinders C1-C6.

[0046] As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention.

[0047] The ship propeller 1 is not limited to an outboard engine, and may be an inboard or outboard engine, or other propellers such as a jet propeller. The configuration of the engine 5 is not limited to that of the above embodiment and may be changed. For example, the number of cylinders of the engine 5 is not limited to six, and may be less than six or more than six. The cylinder arrangement of the engine 5 is not limited to a V-type, and may be other arrangements such as in-line or horizontally opposed.

[0048] The engine rotation sensor 42 is not limited to a magnetic type, and may be of other types such as an optical type. The notification device 45 is not limited to a display, and may be other devices such as a buzzer, a speaker, or a warning lamp.

[0049] The process of misfire monitoring control is not limited to that of the above embodiment and may be changed. For example, the controller 40 may notify the occurrence of misfire when the number of misfires NL is equal to or greater than a predetermined misfire number threshold. The determination of the occurrence of misfire may be performed for each of the plurality of cylinders C1-C6. For example, the controller 40 may notify the occurrence of misfire when the misfire rate or the number of misfires of each of the plurality of cylinders C1-C6 is equal to or greater than a threshold. The determination parameters for determining the occurrence of misfire are not limited to the angular acceleration and angular acceleration deviation of the crankshaft 11. For example, the determination parameter may be an angular jump.

Industrial Applicability

[0050] According to the present invention, in a ship propeller including an engine having a plurality of cylinders, the accuracy of determining misfire in the engine can be improved.

Explanation of Reference Numerals

[0051] 1: Ship propeller 5: Engine 11: Crankshaft 40: Controller 42: Engine rotation sensor 45: Notification device C1: Cylinder C2: Second cylinder

Claims

1. A method for controlling a marine propulsion device comprising an engine including a plurality of cylinders and a crankshaft, the method comprising: obtaining an angular acceleration of the crankshaft; obtaining a determination parameter for determining misfire of the engine based on the angular acceleration of the crankshaft; determining misfire in the engine by comparing the determination parameter with a threshold value set for each of the plurality of cylinders. A method comprising the above.

2. The plurality of cylinders include a first cylinder and a second cylinder, the threshold values include a first threshold value set for the first cylinder and a second threshold value set for the second cylinder and different from the first threshold value, obtaining a first value of the determination parameter at an ignition timing of the first cylinder; obtaining a second value of the determination parameter at an ignition timing of the second cylinder; determining misfire in the engine by comparing the first value with the first threshold value; determining misfire in the engine by comparing the second value with the second threshold value. The method according to claim 1, comprising the above.

3. obtaining a rotational speed of the engine; determining the first threshold value from the rotational speed of the engine with reference to first threshold value data defining a relationship between the first threshold value and the rotational speed of the engine; determining the second threshold value from the rotational speed of the engine with reference to second threshold value data defining a relationship between the second threshold value and the rotational speed of the engine. The method according to claim 2, comprising the above.

4. Further comprising, when it is determined that misfire has occurred in the engine, notifying the occurrence of misfire. The method according to claim 1.

5. The determination parameter includes at least one of the angular acceleration of the crankshaft, a deviation of the angular acceleration, and an angular jerk. The method according to claim 1.

6. A system for controlling a marine propulsion device comprising an engine including a plurality of cylinders and a crankshaft, the system comprising: a sensor for detecting an angular acceleration of the crankshaft; a controller; The system comprising the above, wherein the controller: obtains the angular acceleration of the crankshaft; obtains a determination parameter for determining misfire of the engine based on the angular acceleration of the crankshaft; A system for determining misfire in the engine by comparing the determination parameter with a threshold value set for each of the plurality of cylinders. System.

7. The plurality of cylinders include a first cylinder and a second cylinder. The threshold values include a first threshold value set for the first cylinder and a second threshold value set for the second cylinder and different from the first threshold value. The controller: Obtains a first value of the determination parameter at the ignition timing of the first cylinder. Obtains a second value of the determination parameter at the ignition timing of the second cylinder. Determines misfire in the engine by comparing the first value with the first threshold value. Determines misfire in the engine by comparing the second value with the second threshold value. The system according to claim 6.

8. The controller: Obtains the rotational speed of the engine. Determines the first threshold value from the rotational speed of the engine with reference to first threshold value data defining the relationship between the first threshold value and the rotational speed of the engine. Determines the second threshold value from the rotational speed of the engine with reference to second threshold value data defining the relationship between the second threshold value and the rotational speed of the engine. The system according to claim 7.

9. The system further includes a notification device for notifying the occurrence of misfire in the engine. When the controller determines that misfire has occurred in the engine, the controller controls the notification device to notify the occurrence of misfire. The system according to claim 6.

10. The determination parameter includes at least one of the angular acceleration of the crankshaft, the deviation of the angular acceleration, and the angular jerk. The system according to claim 6.

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