US20240083566A1

US20240083566A1 - Water jet propulsion boat and method of maintaining bow-up attitude of water jet propulsion boat

Info

Publication number: US20240083566A1
Application number: US18/226,288
Authority: US
Inventors: Masakichi SUZUKI
Original assignee: Yamaha Motor Co Ltd
Current assignee: Yamaha Motor Co Ltd
Priority date: 2022-09-12
Filing date: 2023-07-26
Publication date: 2024-03-14
Also published as: JP2024039840A

Abstract

A water jet propulsion boat includes a hull, a drive source in the hull, a jet propulsion mechanism to generate a propulsive force for the hull by ejecting a jet of water with a driving force from the driving source, a jet stream changer to change at least one of a jet stream direction and a jet stream force of the jet of water from the jet propulsion mechanism, a tilt detector to output a detection signal according to a tilt angle of the hull, and a controller configured or programmed to execute an angle difference calculation to calculate an angle difference between the tilt angle of the hull and a target angle of the hull for a bow-up attitude based on the detection signal from the tilt detector, and a feedback process to reduce the angle difference by changing at least one of the jet stream direction or the jet stream force by the jet stream changer.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application No. 2022-144505 filed on Sep. 12, 2022. The entire contents of this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The techniques disclosed herein relate to water jet propulsion boats.

2. Description of the Related Art

Conventionally, water jet propulsion boats have been known to include a jet generator and direction changing member. The jet generator is driven by a driving source such as an engine and generates a jet by ejecting water sucked in from the outside of the hull from the jetting port to rearwardly of the hull. The direction changing member is, e.g., a deflector, that changes the jet stream direction of the jet of water generated by the jet generator. The position of the direction changing member is shifted according to an operation by the steering device disposed on the hull. The user (crew) of such a water jet propulsion boat may wish to put the hull in a bow-up attitude (see, e.g., U.S. Pat. No. 10,864,972, JP Utility Model Application Publication No. H01-099798, JP 2005-324716A).
In the conventional water jet propulsion boat described above, the deflector is placed in a fixed position when the hull is in the bow-up attitude, regardless of the tilt angle of the hull. Therefore, there is room for improvement in the operability of the hull in the bow-up attitude, e.g., smooth transition of the hull to the bow-up attitude and maintaining the bow-up attitude.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide water jet propulsion boats that solve the above-described problems and that are each able to improve the operability of hulls of the water jet propulsion boats with respect to a bow-up attitude.
Preferred embodiments of the present invention disclosed herein may have the following aspects, for example.
A water jet propulsion boat according to a preferred embodiment of the present disclosure includes a hull, a drive source on the hull, a jet propulsion mechanism to generate a propulsive force for the hull by ejecting a jet of water with a driving force from the driving source, a jet stream changer to change at least one of a jet stream direction or a jet stream force of the jet of water from the jet propulsion mechanism, a tilt detector to output a detection signal according to a tilt angle of the hull, and a controller configured or programmed to execute an angle difference calculation to calculate an angle difference between the tilt angle of the hull and a target angle of the hull for a bow-up attitude based on the detection signal from the tilt detector, and to execute a feedback process to reduce the angle difference by changing at least one of the jet stream direction or the jet stream force by the jet stream changer.
According to another preferred embodiment of the present invention, a method of maintaining a bow-up attitude of a water jet propulsion boat including a hull and a jet propulsion mechanism to generate propulsive force of the hull by ejecting a jet of water includes calculating an angle difference between a tilt angle of the hull in an upper-lower direction and a target angle of the hull in the bow-up attitude, and reducing the angle difference in a feedback process by changing at least one of the jet stream direction or the jet stream force of the jet of water from the jet propulsion mechanism.
It should be noted that the preferred embodiments disclosed herein may be implemented in various aspects, such as a water jet propulsion boat, a controller for a bow-up attitude of a water jet propulsion boat, a maintenance method for a bow-up attitude of a water jet propulsion boat, and a non-transitory recording medium storing a computer program for implementing such a method or the function of such a device.
The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view schematically illustrating a configuration of a water jet propulsion boat according to a preferred embodiment of the present invention.

FIGS. 2A to 2C are explanatory views illustrating a side configuration of a nozzle and a deflector.

FIG. 3 is an explanatory view illustrating an external configuration of a steering device.

FIG. 4 is a block diagram illustrating a control configuration of the water jet propulsion boat.

FIG. 5 is a flowchart illustrating a bow-up control process.

FIG. 6 is an explanatory view illustrating an example of the bow-up attitude of the hull.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a side view schematically illustrating a configuration of a water jet propulsion boat 10 according to a preferred embodiment of the present invention. FIG. 1 and other drawings described below show arrows representing each direction with respect to the position of the water jet propulsion boat 10. More specifically, each figure shows arrows representing front (FRONT), rear (REAR), left (LEFT), right (RIGHT), upper (UPPER), and lower (LOWER), respectively. The front-rear direction, the left-right direction (paper depth direction for each drawing, not shown), and the upper-lower (vertical) direction are each perpendicular to each other.
The water jet propulsion boat 10 includes a hull 20, a driving device 30, a jet generator 40, a jet adjustment mechanism 50, a shift mechanism 60, a steering device 70, and a control device (ECU) 80.
The hull 20 includes a hull body 21, a deck 22, and a seat 23. The hull body 21 defines the bottom of the hull 20 and the deck 22 defines the top of hull 20. The seat 23 is located approximately in the center of the hull 20 in the front-rear direction so that a user(crew), not shown, can sit.
The driving device 30 includes an engine 31, a crankshaft 32, and a coupling 33. Within the hull 20, the driving device 30 is disposed in the space defined between the hull body 21 and the deck 22. The engine 31 is a spark-ignited, multi-cylinder internal combustion engine. The engine 31 is disposed below the seat 23. The engine 31 is an example of a drive source. The crankshaft 32 is a rotating shaft that outputs the driving torque generated by the engine 31. The crankshaft 32 extends rearwardly from the driving device 30. The coupling 33 connects the crankshaft 32 with an impeller shaft 45, which will be described below, so that the driving torque of the crankshaft 32 is transmitted to the impeller shaft 45.
The jet generator (water jet propulsion mechanism) 40 is located in the rear portion of the hull body 21 of the hull 20. The jet generator 40 includes a channel 41, an impeller housing 43, an impeller 44, an impeller shaft 45, a stator blade 46, and a nozzle 47.
The channel 41 is located in the rear portion of the hull body 21 of the hull 20 and in the center portion in the left-right direction. One end of the channel 41 opens downward from the hull body 21 as a water suction port 42 to suck in water. The channel 41 extends rearwardly from the water suction port 42, and the other end 41 a of the channel 41 opens rearwardly from the hull body 21.
The impeller housing 43 includes a nearly cylindrical body extending in the front-rear direction and projects from the other end 41 a of the channel 41 rearwardly from the hull body 21. The impeller 44 is housed in the impeller housing 43 and connected to the rear end of the impeller shaft 45. This allows the impeller 44 to rotate integrally with the impeller shaft 45 around the central axis of the impeller shaft 45. The stator blade 46 is disposed behind the impeller 44 in the impeller housing 43. The nozzle 47 is a cylindrical member and is fixed to the rear end 43 a of the impeller housing 43. The rear end of the nozzle 47 opens as a jetting port 48 to eject water therefrom.
With such a configuration, when the driving torque generated by the engine 31 is transmitted to the impeller shaft 45 to rotate the impeller 44, water is sucked into the channel 41 from the outside of the hull 20 (below the hull body 21) through the water suction port 42. The water sucked into the channel 41 is supplied by the impeller 44 to the stator blade 46. The water supplied by the impeller 44 is rectified by passing through the stator blade 46. The rectified water passes through the nozzle 47 and is ejected from the jetting port 48 to rearward of the hull 20. In this way, the jet generator 40 is able to generate a jet of water rearwardly from the hull 20. According to this configuration, the higher the rotation speed of the engine 31, the higher the flow rate of the jet of water ejected from the jet generator 40. Therefore, the amount of water ejected from the jet generator 40 (jet stream force) is adjusted by changing the operating state (rotation speed) of the engine 31. The driving device 30 and the jet generator 40 are examples of a jet stream force changer.
The jet adjustment mechanism 50 includes a deflector 51 and a reverse bucket 52. The deflector 51 is an example of a direction changer.
FIGS. 2A to 2C are explanatory views illustrating a side configuration of a nozzle 47 and a deflector 51. In FIGS. 2A to 2C, the jet stream directions F of the jet determined by the deflector 51 are different from one another. As shown in FIGS. 2A to 2C, the deflector 51 changes the jet stream direction F of the jet generated by the jet generator 40 in the upper-lower direction.
Specifically, as shown in FIG. 1 and FIG. 2 , the deflector 51 is an approximately cylindrical (frusto-conical) member structured so that the inner diameter becomes smaller toward the rearward direction of the hull 20. The deflector 51 is disposed behind the nozzle 47 and covers the jetting port 48 of the nozzle 47 (see FIG. 1 ). Therefore, the jet of water ejected from the jetting port 48 of the nozzle 47 passes through the deflector 51 and is ejected from an ejection port 51 a.
The deflector 51 is pivotable with respect to the hull 20 around a pivot axis extending along the upper-lower direction (vertical direction) and around a pivot axis extending along the left-right direction (horizontal direction). Each of the left and right sides of the deflector 51 is provided with a connecting portion 51 b, and the deflector 51 is turned left and right (around the pivot axis along the upper-lower direction) when an operation cable (not shown) connected to the connecting portion 51 b is operated by a steering handle 71 described below.
A connecting portion 51 c is provided on the upper portion of the deflector 51, and the deflector 51 pivots around the pivot axis along the left and right direction when the connecting portion 51 c is moved by a deflector moving mechanism 61.
The reverse bucket 52 is disposed on the rear side of the deflector 51 (see FIG. 1 ) and is shiftable among a forward position, a neutral position, and a rearward position with respect to the jet generator 40. The forward position does not cover the ejection port 51 a of the deflector 51 (see FIG. 1 ), the neutral position partially covers the ejection port 51 a of the deflector 51, and the rearward position completely covers the ejection port 51 a of the deflector 51.
The shift mechanism 60 includes the deflector moving mechanism 61 and a reverse bucket moving mechanism 65 (see FIG. 1 ).
The deflector moving mechanism 61 shifts the deflector 51 according to the operation by the steering device 70. Specifically, as shown in FIGS. 2A to 2C, the deflector moving mechanism 61 includes a trim actuator 62, a trim arm 67, and a link 64. The trim actuator 62 may be a well-known servomotor. The trim actuator 62 includes an output shaft 62 a. The trim actuator 62 is arranged so that the center axis of the output shaft 62 a is parallel or substantially parallel to the left and right direction of the hull 20. The trim arm 67 extends upward from the output shaft 62 a in the vertical direction. The trim arm 67 is fixed at its lower end so as to be integrally rotatable with the output shaft 62 a. The link 64 connects the trim arm 67 and the deflector 51 (connecting portion 51 c).
As shown in FIG. 2A, the direction of the center axis of the deflector 51 is parallel or substantially parallel to the horizontal line L when the longitudinal direction of the trim arm 67 is perpendicular or substantially perpendicular to the horizontal line L of the hull 20 (i.e., when the trim arm 67 is in the reference position Pb1). At this time, the jet of water ejected from the jetting port 48 of the nozzle 47 (hereinafter also referred to simply as the “nozzle jet”) is ejected from the ejection port 51 a to the rearward of the hull 20 parallel or substantially parallel to horizontal line L after passing through the deflector 51. The pivot position of the deflector 51 at this time is called the “neutral position”.
As shown in FIG. 2B, the direction of the center axis of the deflector 51 is set downward with respect to the horizontal line L when the trim arm 67 is at a position Pd rotated clockwise (right-handed rotation) by a predetermined angle α1 in the side view from the reference position Pb1. At this time, after passing through the deflector 51, the nozzle jet is ejected from the ejection port 51 a to the rearward of the hull 20 obliquely downward with respect to the horizontal line L. The pivot position of the deflector 51 at this time is called the “downward position.”
As shown in FIG. 2C, the direction of the center axis of the deflector 51 is set upward with respect to the horizontal line L when the trim arm 67 is at a position Pu rotated counterclockwise (left-handed rotation) by a predetermined angle α2 in the side view from the reference position Pb1. At this time, after passing through the deflector 51, the nozzle jet is ejected from the ejection port 51 a to the rearward of the hull 20 obliquely upward with respect to the horizontal line L. The pivot position of the deflector 51 at this time is called the “upward position.” Furthermore, the deflector moving mechanism 61 sets the rotational position of the trim arm 67 to any position between positions Pu and Pd (including positions Pu and Pd) in a stepless manner, for example.
With such a configuration, the deflector 51 is arranged pivotably around the vertical axis and the horizontal axis behind the jetting port 48. Therefore, the deflector 51 is able to change the left-right direction and the upper-lower direction of the jet of water ejected from the jetting port 48 to the rearward of the hull 20 according to its pivot position.
The reverse bucket moving mechanism 65 includes a shift actuator 66. The shift actuator 66 shifts the reverse bucket 52.
Further, in the shift mechanism 60, an operation by the steering device 70 is transmitted to the trim actuator 62 and the shift actuator 66 by electric control. For example, the steering device 70 includes sensors 81 and 82, among others, which detect various operations to be described below, and the trim actuator 62 and the shift actuator 66 are controlled according to the operation by the steering device 70 based on the output signals from the sensors 81, 82 which detect various operations of the steering device 70.
FIG. 3 is an explanatory view illustrating an external configuration of the steering device 70. FIG. 3 shows an external configuration around a steering handle 71 as seen from the user seated on the seat 23. As shown in FIG. 3 , the steering device 70 includes a steering handle 71, a right grip portion 72R, a left grip portion 72L, a first operator 73, a second operator 74, a third operator 75, a start switch 76, a stop switch 77, and a display unit 78.
The steering handle 71 includes a pair of bar-shaped sections extending in the left-right direction with respect to the hull 20 and is supported pivotably around a pivot axis extending along the upper-lower direction. The right grip portion 72R is provided on the right side of the steering handle 71, and the left grip portion 72L is provided on the left side of the steering handle 71. The user of the water jet propulsion boat 10 is able to turn the steering handle 71 by gripping the right grip portion 72R and the left grip portion 72L. When the steering handle 71 is turned, the deflector 51 is turned in the left-right direction via the shift mechanism 60.
The first operator 73 includes a lever that is able to be moved by the user within a predetermined first range to change the operation amount (amount of driving operation). The lever of the first operator 73 is pivotably supported near the base end of the right grip portion 72R. The operation amount (i.e., the amount of movement of the lever) of the first operator 73 is detected by a first position sensor 81 disposed at an upper portion of the first operator 73. The first position sensor 81 may be a well-known potentiometer. In a state where a predetermined forward operation is performed on the lever of the first operator 73, the output (rotation speed) of the engine 31 is changed according to the operation amount of the first operator 73. Thus, the first operator 73, the operation amount of which is changeable, is operated mainly when the water jet propulsion boat 10 is moved forward.
The second operator 74 includes a lever that is able to be moved by the user within a predetermined second range to change the operation amount (amount of driving operation). The lever of the second operator 74 is pivotably supported near the base end of the left grip portion 72L. The operation amount (i.e., the amount of movement of the lever) of the second operator 74 is detected by a second position sensor 82 disposed at an upper portion of the second operator 74. The second position sensor 82 may be a well-known potentiometer. In a state where a predetermined reverse operation described below is performed on the lever of the second operator 74, the output (rotation speed) of the engine 31 is changed according to the operation amount of the second operator 74. Thus, the second operator 74, the operation amount of which is changeable, is operated mainly when the water jet propulsion boat 10 is moved rearward.
The third operator 75 is, e.g., a push-button switch and includes an up switch 75 a and a down switch 75 b (see FIG. 4 below). The third operator 75 is disposed, e.g., near the left grip portion 72L and on the inner side of the left grip portion 72L in the left-right direction. Therefore, the user can easily operate the third operator 75 with the left thumb while holding the left grip portion 72L with the left hand. When the third operator 75 is operated, the position of the jet adjustment mechanism 50 (deflector 51, reverse bucket 52) is changed according to the operation. Hereafter, the operation of the third operator 75 to change the pivot position of the deflector 51 is referred to as the “trim operation.”
The start switch 76 is disposed on the front side surface of the steering handle 71 near the third operator 75. The start switch 76 is a switch to start the engine 31, such as a push-button switch.
The stop switch 77 is disposed on the rear-side surface of the steering handle 71 to the right of the third operator 75. The stop switch 77 is a switch to stop the engine 31, such as a push-button switch.
A display unit 78 is located in the center of the steering handle 71. The display unit 78 may be, e.g., a liquid crystal display and displays drawings and the like. The display unit 78 may have a touch panel to function as an operation reception unit that accepts an operation performed by the user. In FIG. 3 , a portion X1 of the display unit 78 is shown in an enlarged view.
FIG. 4 is a block diagram illustrating a control configuration of the water jet propulsion boat 10. As shown in FIG. 4 , the driving device 30 includes a fuel injector 34, a throttle actuator 35, a throttle valve 36, and an igniter 37. The fuel injector 34 supplies fuel to a combustion chamber (not shown) of the engine 31. The throttle actuator 35 changes the opening of the throttle valve 36 (hereinafter referred to as “throttle opening”). The throttle valve 36 adjusts the amount of intake air of the engine 31. The throttle valve 36 is shared by a plurality of cylinders of the engine 31. The igniter 37 ignites the fuel (mixture) in the combustion chamber. The fuel injector 34 and the igniter 37 are provided in each cylinder of the engine 31, respectively. The throttle valve 36 may be provided in each cylinder of the engine 31.
The ECU 80 is an abbreviation for electronic control unit and includes CPU 80 a, ROM 80 b, RAM 80 c, backup RAM (or non-volatile memory not shown), and interface I/F (not shown). The CPU 80 a implements various functions by executing instructions (routines) stored in a memory (ROM 80 b). ECU 80 is an example of a controller.
The ECU 80 is electrically connected to the fuel injector 34, the throttle actuator 35, and the igniter 37. The ECU 80 is electrically connected to the third operator 75, the start switch 76, the stop switch 77, the first position sensor 81, the second position sensor 82, a third position sensor 83, a fourth position sensor 84, a rotation speed sensor 85, the display unit 78, and a gyro-sensor 86. The ECU 80 is configured or programmed to receive output signals from these switches and sensors.
The first position sensor 81 is configured to generate an output signal representing the operation amount (first accelerator operation amount) Am1 of the first operator 73. The second position sensor 82 is configured to generate an output signal representing the operation amount (second accelerator operation amount) Am2 of the second operator 74. The third position sensor 83 is configured to generate an output signal representing the rotation angle α of the trim actuator 62. The fourth position sensor 84 is configured to generate an output signal representing the rotation angle β of the shift actuator 66. The rotation speed sensor 85 is configured to generate an output signal representing the rotation speed Ne of the crankshaft 32. The gyro-sensor 86 generates a detection signal according to the attitude of the hull 20, and the ECU 80 specifies the tilt angle θ (attitude) in the vertical direction of the hull 20 and the angular velocity V (amount of change in the angle θ per unit time and direction of change in the angle (bow-up or bow-down direction)) based on the detection signal from the gyro-sensor 86. The gyro-sensor 86 is an example of a tilt detector.
The ECU 80 is configured or programmed to move the reverse bucket 52 to the forward position when the engine 31 is stopped. In addition, the ECU 80 is configured or programmed to move the reverse bucket 52 from the forward position to the neutral position when the engine 31 is started. The sailing mode in which the reverse bucket 52 is moved from the forward position to the neutral position is sometimes referred to as the neutral mode.
If the first operator 73 is operated when the reverse bucket 52 is in the neutral position and the first operation amount Am1 is equal to or greater than a predetermined operation amount, the ECU 80 moves the reverse bucket 52 to the forward position and increases the opening of the throttle valve 36 according to the size of the first operation amount Am1. Such a sailing mode is sometimes referred to as a forward mode.
If the second operator 74 is operated when the reverse bucket 52 is in the neutral position and the second operation amount Am2 is equal to or greater than a predetermined operation amount, the ECU 80 moves the reverse bucket 52 to the reverse position and increases the opening of the throttle valve 36 according to the size of the second operation amount Am2. Such a sailing mode is sometimes referred to as a reverse mode.
FIG. 5 is a flowchart illustrating a bow-up control process. The bow-up control process is a process to improve the operability of the hull 20 with respect to the bow-up attitude, such as a smooth transition of the hull 20 to the bow-up attitude and maintaining the bow-up attitude. In the bow-up attitude, the hull 20 is tilted so that the bow of the hull 20 is positioned above the stern.
FIG. 6 is an explanatory view illustrating an example of the bow-up attitude of the hull 20. The symbol “θ” in FIG. 6 represents the tilt angle of the hull 20 with respect to the reference horizontal line L in the vertical direction, and when the hull 20 is in the bow-up attitude, the tilt angle θ will have a positive value. The symbol “θt” represents the target range of the tilt angle of the hull 20 in the bow-up attitude. The sign “Δθ” is the relative angle difference of the tilt angle θ with respect to the target range θt (e.g., the center angle of the target range θt), and the sign “θs” is the trigger angle that triggers the feedback process described below. The trigger angle θs is smaller than the lower limit angle of the target range θt. The tilt angle θ of the hull 20 in the bow-up attitude may be, e.g., about 15 degrees or more, or even about 30 degrees or more. The target range θt is an example of a target angle. The target angle may be a predetermined angle.
As described below, the bow-up control process includes a feedback process (see S150 and S160 of FIG. 5 ). In the feedback process according to the present preferred embodiment, a combined control mode is executed in which the relative angle difference Δθ of the tilt angle θ with respect to the target range θt is reduced by changing the jet stream direction F of the nozzle jet by shifting the deflector 51 and changing the jet stream force (propulsion force) of the nozzle jet by the driving device 30.
For example, in a case where the tilt angle θ of the hull 20 is smaller than the target range θt (see FIG. 6 ), when the ECU 80 further shifts the pivot position of deflector 51 (hereinafter referred to as “trim position”) toward the upward position, a rotational force that moves the bow of hull 20 farther upward acts on hull 20, which reduces the angle difference Δθ. Further, when the ECU 80 increases the throttle opening, if the trim position is at the start position, a propulsive force is exerted on the hull 20 that moves the bow of the hull 20 farther upward to reduce the angle difference Δθ. In contrast, in a case where the tilt angle θ of the hull 20 is larger than the target range θt, when the ECU 80 shifts the trim position to the neutral position, the rotational force that moves the bow of the hull 20 downward acts to reduce the angle difference Δθ. In addition, when the ECU 80 decreases the throttle opening, if the trim position is at the start position, the propulsive force that moves the bow of the hull 20 upward decreases, which reduces the angle difference Δθ.
The user can set the bow-up mode, e.g., by performing a predetermined operation (e.g., touch panel operation at the display unit 78 above) with the steering device 70. In this case, the user can select either a full-assist mode or a semi-assist mode for the bow-up mode. When the bow-up mode is set, the ECU 80 performs the bow-up control process shown in FIG. 5 .
As shown in FIG. 5 , the ECU 80 first controls the trim actuator 62 to place the trim position at the start position (S110). The start position is on the upward side of the above neutral position (see FIG. 6 ), and may be, e.g., a position where it is easy to shift from a non-bow-up attitude (e.g., a normal attitude in which the hull 20 is parallel or substantially parallel to the horizontal line L (see FIG. 1 )) to a bow-up attitude, or a position where it is easy to maintain a bow-up attitude.
The ECU 80 also causes the display unit 78 to display tilt-related information according to the tilt angle θ of the hull 20 based on the detection signal from the gyro-sensor 86 (S110). The tilt-related information is information that graphically displays the tilting state of the hull 20 in the upper-lower direction as shown in the portion X1 of FIG. 3 . Specifically, a simplified symbol 20 a of the hull 20 and the value of the tilt angle in the vertical direction with respect to the horizontal line L at each predetermined angle interval (e.g., 10 degrees) are displayed on the display unit 78. The simplified symbol 20 a tilts up and down in conjunction with the tilt angle θ of the hull 20. Therefore, since the user is able to visually grasp the tilting state of the hull 20 by viewing the display on the display unit 78, the operability of the hull 20 with respect to the bow-up attitude is further enhanced, e.g., by shifting weight in response to the display.
Next, the ECU 80 detects the tilt angle θ of the hull 20 (S120) and determines whether the tilt angle θ of the hull 20 is greater than or equal to the trigger angle θs (S130). The user can make the tilt angle θ of the hull 20 greater than or equal to the trigger angle θs by attempting the bow-up action of moving his body weight to the stern side of the hull 20 while operating the first operator 73 (hereinafter referred to as “throttle operation”). If the user attempts a bow-up action but the tilt angle θ of the hull 20 is less than the trigger angle θs (S130: No), the process returns to S120 again. On the other hand, if the tilt angle θ of the hull 20 becomes equal to or greater than the trigger angle θs (S130: Yes) as a result of the user-attempted bow-up action, the process proceeds to S140 to start the feedback process and the like. In other words, the ECU 80 starts the feedback process on the condition that the tilt angle θ of the hull 20 reaches the trigger angle θs. This reduces or prevents unwanted execution of the feedback process when the hull 20 is in a non-bow-up attitude.
In S140, the ECU 80 calculates the tilt angle θ and angular velocity V of the hull 20 based on the detection signal from the gyro-sensor 86 (S140). The process in S140 is an example of an angular velocity calculation. The ECU 80 then calculates the relative angle difference Δθ of the tilt angle θ with respect to the target range θt based on the calculated tilt angle θ, and calculates the moving direction of the tilt of the hull 20 in the upper-lower direction (hereinafter referred to as the “tilting direction R”, see FIG. 6 ) based on the calculated angular velocity V (positive or negative) (S150). The process in S150 is an example of an angle difference calculation.
Next, the ECU 80 performs the feedback process (S160, S170). This process is an example of the feedback step. In the feedback process, the above combined control mode is executed based on the angular velocity V in addition to the tilt angle θ of the hull 20. Thus, the jet stream direction F and the jet stream force of the nozzle jet are changed according to the angular velocity V of the tilt angle θ, which indicates the tilting direction R of the hull 20. Therefore, it is possible to efficiently reduce the above angle difference Δθ in the bow-up attitude, compared to the configuration in which the angular velocity V is not considered.
In the present preferred embodiment, the contents of the feedback process are different between the full-assist mode and the semi-assist mode. The full-assist mode is an example of a second combined control mode and a fourth combined control mode, and the semi-assist mode is an example of a first combined control mode and a third combined control mode.
When the full-assist mode is selected (S160), the feedback process by the ECU 80 is performed in a state where the user operation of the steering device 70 (throttle operation, trim operation) is disabled.
Specifically, the ECU 80 calculates the “angle changed by trim control” and the “angle changed by throttle opening” based on the calculated angle difference Δθ and angular velocity V. The angle changed by the trim control is a predicted value of the tilt angle θ of the hull 20 due to a change in the trim position (rotation amount of the deflector 51). The angle changed by the throttle opening is the predicted value of the changing angle of the tilt angle θ of the hull 20 due to a change in the throttle opening. For the angle changed by the trim control and the angle changed by the throttle opening, the optimum value required to reduce the angle difference Δθ of the hull 20 is calculated, respectively. In the full-assist mode, the angle difference Δθ, the angle changed by trim control, and the angle changed by throttle opening can be expressed, e.g., by the following equation 1.
|angle difference Δθ|−|K*(K1(angle changed by trim control)+K2*(angle changed by throttle opening))|=0 EQUATION 1
It should be noted that the total angle of the angle changed by trim control and the angle changed by throttle opening may be multiplied by a factor K to account for control errors such as lag in the feedback control process, for example. In addition, the angle changed by trim control and the angle changed by throttle opening may be multiplied by different coefficients K1 and K2 to give different weighting. The full-assist mode improves the operability of the hull 20 with respect to the bow-up attitude, e.g., a smooth transition of the hull 20 to the bow-up attitude and maintaining the bow-up attitude, without relying on user operation.
When the semi-assist mode is selected (S170), the feedback process by the ECU 80 is performed in a state where the user operation of the steering device 70 (throttle operation, trim operation) is enabled.
Specifically, the ECU 80 calculates the angle changed by trim control and the angle changed by throttle opening based on the “angle changed by operation” in addition to the calculated angle difference Δθ and angular velocity V. The angle changed by operation is a predicted value of the tilt angle θ of the hull 20 due to the user operation of the steering device 70 (throttle operation and trim operation). In the semi-assist mode, the angle difference Δθ, the angle changed by trim control, the angle changed by throttle opening, and the angle changed by operation can be expressed, e.g., by the following equation 2.
|angle difference Δθ|−|K*(K1(angle changed by trim control)+K2(angle changed by throttle opening))+K3 (angle changed by operation))|=0 EQUATION 2
It should be noted that the angle to be changed may be multiplied by a factor K3 to account for control errors such as lag of the shift mechanism 60 to the operation of the steering device 70. The semi-assist mode improves the operability of the hull 20 with respect to the bow-up attitude, e.g., the smooth transition of the hull 20 to the bow-up attitude and maintaining the bow-up attitude, while allowing the user operation and reflecting the change in the jet stream direction F and the jet stream force of the nozzle jet.
The processes of S140 to S160 and S170 are repeated until the bow-up is canceled. The bow-up may be canceled by an operation to cancel the bow-up mode setting in the steering device 70 or by the user shifting the weight to the bow side of the hull 20 to bring the hull 20 into a non-bow-up attitude (e.g., the tilt angle θ is less than or equal to the trigger angle θs). If the bow-up attitude is not canceled (S180: No) after the execution of the feedback process (S160, S170), the ECU 80 returns the process to S140. On the other hand, if the bow-up is canceled (S180: Yes), the ECU 80 stops the feedback process and terminates the current bow-up control process.
The present invention is not limited to the preferred embodiments described above and may be modified in various ways without departing from the spirit of the present invention, including the following modifications.
The configuration of the water jet propulsion boat 10 of the above-described preferred embodiments is only an example and may be variously modified. For example, in the above preferred embodiments, the engine 31 is exemplified as the driving source of the driving device 30, but it is not limited to this, e.g., an electric motor or the like may be used. In the above preferred embodiments, the deflector 51 is exemplified as the direction changer, but the present invention may be applied to, e.g., the reverse bucket 52.
In the above-described preferred embodiments, a trim actuator 62 powered by a servomotor is exemplified, but the trim actuator 62 may be an electric actuator utilizing another driving source (e.g., a solenoid or an electric motor). In addition, the trim actuator 62 may be an actuator utilizing other driving sources (e.g., magnetic fluid actuators, electrorheological fluid actuators, and hydraulic actuators).
In the above-described preferred embodiments, electric control by wireline communication is exemplified as the transmission mechanism to transmit the operation by the steering device 70 to, e.g., the trim actuator 62, but it is not limited to this, and electric control by wireless communication may be used. In addition, the transmission mechanism may be configured such that the steering handle 71 and the trim actuator 62 or the like are mechanically connected by an operating cable, and the deflector 51 is shifted by the amount of movement corresponding to the amount of movement of the steering handle 71.
The content of the bow-up control process (FIG. 5 ) in the above-described preferred embodiments is only an example and may be variously modified. For example, in the above preferred embodiments, in the feedback process, the combined control mode is executed, but the jet stream direction control mode or the jet stream force control mode may be executed. The jet stream direction control mode is a mode that shifts the deflector 51 to change the jet stream direction F of the nozzle jet, thus reducing the relative angle difference Δθ of the tilt angle θ with respect to the target range θt without changing the jet stream force of the nozzle jet by the driving device 30 or the like. The jet stream force control mode is a mode that causes the driving device 30 or the like to change the jet stream force of the nozzle jet thus reducing the relative angle difference Δθ without changing the jet stream direction F of the nozzle jet with the shift of the deflector 51.
In the bow-up control process of the above-described preferred embodiments (e.g., FIG. 5 ), it is not necessary to display the tilt-related information according to the tilt angle θ of the hull 20 on the display unit 78. In addition, the ECU 80 may start the feedback process without the condition that the tilt angle θ of the hull 20 reaches the trigger angle θs. The ECU 80 may also specify the tilting direction R based on a detection signal from, e.g., the gyro-sensor 86, without calculating the angular velocity V of the hull 20.
In the bow-up control process of the above-described preferred embodiments (e.g., FIG. 5 ), the ECU 80 may increase the rate of change of at least one of the jet stream direction or the jet stream force by the jet stream changing unit as the calculated angular velocity V increases. At this time, the ECU 80 may, e.g., change the jet stream direction according to the angle difference Δθ and change the jet stream force according to the rate of change. The ECU 80 may perform either a full-assist mode (S160) or a semi-assist mode (S170). In the semi-assist mode (S170), either the throttle operation or the trim operation may be enabled. The jet stream changing unit may be configured to change either the jet stream direction or the jet stream force of jet from the jet propulsion mechanism to perform the feedback process.
While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.

Claims

What is claimed is:

1. A water jet propulsion boat comprising:

a hull;

a drive source in the hull;

a jet propulsion mechanism to generate a propulsive force for the hull by ejecting a jet of water with a driving force from the driving source;

a jet stream changer to change at least one of a jet stream direction or a jet stream force of the jet of water from the jet propulsion mechanism;

a tilt detector to output a detection signal according to a tilt angle of the hull; and

a controller configured or programmed to execute:

an angle difference calculation to calculate an angle difference between the tilt angle of the hull and a target angle of the hull for a bow-up attitude based on the detection signal from the tilt detector; and

a feedback process to reduce the angle difference by changing at least one of the jet stream direction or the jet stream force by the jet stream changer.

2. The water jet propulsion boat according to claim 1, wherein

the controller is configured or programmed to execute an angular velocity calculation to calculate an angular velocity of the tilt angle of the hull based on the detection signal from the tilt detector; and

in the feedback process, at least one of the jet stream direction or the jet stream force is changed by the jet stream changer according to the angular velocity of the tilt angle.

3. The water jet propulsion boat according to claim 2, wherein the controller is configured or programmed to increase, in the feedback process, a rate of change of at least one of the jet stream direction or the jet stream force by the jet stream changer as the angular velocity of the tilt angle increases.

4. The water jet propulsion boat according to claim 1, wherein

the jet stream changer includes a direction changer to change the jet stream direction of the jet of water from the jet propulsion mechanism; and

the controller is configured or programmed to execute, in the feedback process, a jet stream direction control mode to change the jet stream direction with the direction changer to reduce the angle difference.

5. The water jet propulsion boat according to claim 4, further comprising:

a steering device on the hull; wherein

the jet stream changer is operable to change the jet stream force according to an operation by the steering device to change the jet stream force; and

the jet stream direction control mode includes a first jet stream direction control mode to reduce the angle difference while allowing a change in the jet stream force according to the operation by the steering device.

6. The water jet propulsion boat according to claim 5, wherein

the jet stream direction control mode further includes a second jet stream direction control mode to reduce the angle difference while prohibiting the change of the jet stream force according to the operation by the steering device; and

the controller is configured or programmed to selectively execute the first jet stream direction control mode and the second jet stream direction control mode in the feedback process.

7. The water jet propulsion boat according to claim 4, further comprising:

a steering device on the hull; wherein

the direction changer is operable to change the jet stream direction according to an operation by the steering device to change the jet stream direction;

the jet stream direction control mode includes a third jet stream direction control mode to reduce the angle difference while allowing a change in the jet stream direction according to the operation by the steering device, and a fourth jet stream direction control mode to reduce the angle difference while prohibiting a change in the jet stream direction according to the operation by the steering device; and

the controller is configured or programmed to selectively execute the third jet stream direction control mode and the fourth jet stream direction control mode in the feedback process.

8. The water jet propulsion boat according to claim 1, wherein

the jet stream changer includes a jet stream force changer to change the jet stream force of the jet of water from the jet propulsion mechanism; and

the controller is configured or programmed to executes in the feedback process, a jet stream force control mode to change the jet stream force by the jet stream force changer to reduce the angle difference.

9. The water jet propulsion boat according to claim 8, further comprising:

a steering device on the hull; wherein

the jet stream force changer is operable to change the jet stream force according to an operation by the steering device to change the jet stream force; and

the jet stream force control mode includes a first jet stream force control mode to reduce the angle difference while allowing a change in the jet stream force according to the operation by the steering device.

10. The water jet propulsion boat according to claim 9, wherein

the jet stream force control mode further includes a second jet stream force control mode to reduce the angle difference while prohibiting the change of the jet stream force according to the operation by the steering device; and

the controller is configured or programmed to selectively execute the first jet stream force control mode and the second jet stream force control mode in the feedback process.

11. The water jet propulsion boat according to claim 8, further comprising:

a steering device on the hull; wherein

the jet stream changer further includes a direction changer to change the jet stream direction of the jet of water from the jet propulsion mechanism;

the jet stream force control mode includes a third jet stream force control mode to reduce the angle difference while allowing a change in the jet stream direction according to the operation by the steering device, and a fourth jet stream force control mode to reduce the angle difference while prohibiting a change in the jet stream direction according to the operation by the steering device; and

the controller is configured or programmed to selectively execute the third jet stream force control mode and the fourth jet stream force control mode in the feedback process.

12. The water jet propulsion boat according to claim 1, wherein

the jet stream changer includes a direction changer to change the jet stream direction of the jet of water from the jet propulsion mechanism and a jet stream force changer to change the jet stream force of the jet of water from the jet propulsion mechanism; and

the controller is configured or programmed to execute, in the feedback process, a combined control mode to change the jet stream direction and the jet stream force by the jet stream force changer to reduce the angle difference.

13. The water jet propulsion boat according to claim 12, further comprising:

a steering device on the hull; wherein

the combined control mode includes a first combined control mode to reduce the angle difference while allowing a change in the jet stream force according to the operation by the steering device.

14. The water jet propulsion boat according to claim 13, wherein

the combined control mode further includes a second combined control mode to reduce the angle difference while prohibiting the change of the jet stream force according to the operation by the steering device; and

the controller is configured or programmed to selectively execute the first combined control mode and the second combined control mode in the feedback process.

15. The water jet propulsion boat according to claim 12, further comprising:

a steering device on the hull; wherein

the combined control mode includes a third combined control mode to reduce the angle difference while allowing a change in the jet stream direction according to the operation by the steering device, and a fourth combined control mode to reduce the angle difference while prohibiting a change in the jet stream direction according to the operation by the steering device; and

the controller is configured or programmed to selectively execute the third combined control mode and the fourth combined control mode in the feedback process.

16. The water jet propulsion boat according to claim 1, wherein the controller is configured or programmed to start the feedback process based on the detection signal from the tilt detector if the tilt angle of the hull reaches a trigger angle smaller than the target angle.

17. The water jet propulsion boat according to claim 1, further comprising:

a steering device on the hull and including a display; wherein

the controller is configured or programmed to cause the display to display tilt-related information according to the tilt angle of the hull based on the detection signal from the tilt detector.

18. A method of maintaining a bow-up attitude of a water jet propulsion boat including a hull and a jet propulsion mechanism to generate a propulsive force of the hull by ejecting a jet of water, the method comprising:

calculating an angle difference between a tilt angle of the hull in an upper-lower direction and a target angle of the hull in the bow-up attitude; and

reducing the angle difference in a feedback process by changing at least one of a jet stream direction or a jet stream force of the jet of water from the jet propulsion mechanism.

19. The method of maintaining a bow-up attitude of a water jet propulsion boat according to claim 18, further comprising:

calculating an angular velocity of the tilt angle of the hull; wherein

in the feedback process, at least one of the jet stream direction or the jet stream force is changed according to the angular velocity of the tilt angle.

20. The method of maintaining a bow-up attitude of a water jet propulsion boat according to claim 19, wherein

in the feedback process, a rate of change of at least one of the jet stream direction or the jet stream force is increased as the angular velocity of the tilt angle increases.