JET PROPULSION SYSTEM AND JET PROPULSION WATERCRAFT

Abstract

A jet propulsion system includes a jet propulsion mechanism including a nozzle, a steering actuator to rotate the nozzle in a right-left direction to change an orientation of a jet of water from a jetting port in the right-left direction, and a controller configured or programmed to, when a person has fallen overboard from a watercraft body, perform a turning control to point a stern toward the person who has fallen overboard by ejecting the jet of water from the nozzle and rotating the watercraft body using the steering actuator.

Claims

1. A jet propulsion system comprising: a jet propulsion mechanism located at a stern of a watercraft body and including a nozzle including a jetting port to eject a jet of water to generate a propulsive force; a steering actuator to rotate the nozzle in a right-left direction to change an orientation of the jet of water from the jetting port in the right-left direction; and a controller configured or programmed to, when a person has fallen overboard from the watercraft body, perform a turning control to point the stern toward the person who has fallen overboard by ejecting the jet of water from the nozzle and rotating the watercraft body using the steering actuator.

2. The jet propulsion system according to claim 1, further comprising: a communicator on the watercraft body; and a location information transmitter carried by the person who has fallen overboard to transmit location information of the person to the communicator; wherein the controller is configured or programmed to, when the person has fallen overboard from the watercraft body, perform the turning control to rotate the watercraft body to point the stern toward the location information transmitter based on the location information.

3. The jet propulsion system according to claim 2, wherein the location information transmitter includes a remote control to receive an automatic return instruction to automatically move the watercraft body to a standby position in a vicinity of the person who has fallen overboard; and the controller is configured or programmed to, when the person has fallen overboard from the watercraft body, perform the automatic return to the standby position based on the location information and an automatic return signal instructing the controller to start the automatic return, both of which are received from the remote control, and perform the turning control to rotate the watercraft body to point the stern toward the remote control based on the location information.

4. The jet propulsion system according to claim 3, wherein the controller is configured or programmed to, during the automatic return, perform the turning control, and then perform a control to move the watercraft body backward to the standby position while pointing the stern toward the remote control.

5. The jet propulsion system according to claim 4, wherein the controller is configured or programmed to, during the automatic return, perform a control to move the watercraft body forward, perform the turning control to point the stern toward the remote control at an intermediate position of the automatic return, and then perform a control to move the watercraft body backward to the standby position.

6. The jet propulsion system according to claim 5, wherein the controller is configured or programmed to, during the automatic return, reduce a speed at which the watercraft body is moved backward as compared with a speed at which the watercraft body is moved forward.

7. The jet propulsion system according to claim 5, wherein the controller is configured or programmed to: move the watercraft body forward to the intermediate position that is a predetermined distance greater than a standby distance from the remote control to the standby position, and then perform the turning control to point the stern toward the remote control when a watercraft body distance from the remote control to the watercraft body is greater than the predetermined distance at a time at which the controller receives the automatic return signal from the remote control; and immediately perform the turning control when the watercraft body distance is equal to or less than the predetermined distance at the time at which the controller receives the automatic return signal from the remote control.

8. The jet propulsion system according to claim 7, wherein the predetermined distance is 5 m or more and 15 m or less.

9. The jet propulsion system according to claim 7, wherein the standby distance is 1 m or more and 3 m or less.

10. The jet propulsion system according to claim 3, wherein the controller is configured or programmed to perform the automatic return to the standby position of the watercraft body along a straight path linearly connecting the remote control and the watercraft body.

11. The jet propulsion system according to claim 1, further comprising: a jet drive source to drive the jet propulsion mechanism to eject the jet of water; and a lanyard including a first end held by the person who has fallen overboard and a second end removably connected to the watercraft body; wherein the controller is configured or programmed to maintain a drive state of the jet drive source and stop movement of the watercraft body when the lanyard is removed from the watercraft body.

12. The jet propulsion system according to claim 1, wherein the stern of the watercraft body includes a reboarding step to enable the person who has fallen overboard to put his or her foot thereon when boarding the watercraft body; and the controller is configured or programmed to, when the person has fallen overboard from the watercraft body, perform the turning control to rotate the watercraft body to point the stern including the reboarding step toward the person who has fallen overboard.

13. A jet propulsion watercraft comprising: a watercraft body; a jet propulsion mechanism located at a stern of the watercraft body including a nozzle including a jetting port water to eject a jet of water to generate a propulsive force; a steering actuator to rotate the nozzle in a right-left direction to change an orientation of the jet of water from the jetting port in the right-left direction; and a controller configured or programmed to, when a person has fallen overboard from the watercraft body, perform a turning control to point the stern toward the person who has fallen overboard by ejecting the jet of water from the nozzle and rotating the watercraft body using the steering actuator.

14. The jet propulsion watercraft according to claim 13, further comprising: a communicator on the watercraft body to communicate with a location information transmitter carried by the person who has fallen overboard to transmit location information of the person who has fallen overboard; wherein the controller is configured or programmed to, when the person has fallen overboard from the watercraft body, perform the turning control to rotate the watercraft body to point the stern toward the location information transmitter based on the location information.

15. The jet propulsion watercraft according to claim 14, wherein the location information transmitter includes a remote control to receive an automatic return instruction to automatically move the watercraft body to a standby position in a vicinity of the person who has fallen overboard; and the controller is configured or programmed to, when the person has fallen overboard from the watercraft body, perform the automatic return to the standby position based on the location information and an automatic return signal instructing the controller to start the automatic return, both of which are received from the remote control, and perform the turning control to rotate the watercraft body to point the stern toward the remote control based on the location information.

16. The jet propulsion watercraft according to claim 15, wherein the controller is configured or programmed to, during the automatic return, perform the turning control, and then perform a control to move the watercraft body backward to the standby position while pointing the stern toward the remote control.

17. The jet propulsion watercraft according to claim 16, wherein the controller is configured or programmed to, during the automatic return, perform a control to move the watercraft body forward, perform the turning control to point the stern toward the remote control at an intermediate position of the automatic return, and then perform a control to move the watercraft body backward to the standby position.

18. The jet propulsion watercraft according to claim 17, wherein the controller is configured or programmed to, during the automatic return, reduce a speed at which the watercraft body is moved backward as compared with a speed at which the watercraft body is moved forward.

19. The jet propulsion watercraft according to claim 17, wherein the controller is configured or programmed to: move the watercraft body forward to the intermediate position that is a predetermined distance greater than a standby distance from the remote control to the standby position, and then perform the turning control to point the stern toward the remote control when a watercraft body distance from the remote control to the watercraft body is greater than the predetermined distance at a time at which the controller receives the automatic return signal from the remote control; and immediately perform the turning control when the watercraft body distance is equal to or less than the predetermined distance at the time at which the controller receives the automatic return signal from the remote control.

20. The jet propulsion watercraft according to claim 19, wherein the predetermined distance is 5 m or more and 15 m or less.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 is a side view showing a jet propulsion watercraft on which a jet propulsion system is mounted according to an example embodiment of the present invention.

[0032] FIG. 2 is an enlarged side view showing a portion of a jet propulsion watercraft on which a jet propulsion system is mounted according to an example embodiment of the present invention.

[0033] FIG. 3 is a block diagram of a jet propulsion system according to an example embodiment of the present invention.

[0034] FIG. 4 is a diagram showing a jet propulsion watercraft and a wireless controller configured or programmed to communicate wirelessly with the jet propulsion watercraft according to an example embodiment of the present invention.

[0035] FIG. 5 is a diagram showing a display screen of a wireless controller of a jet propulsion system according to an example embodiment of the present invention.

[0036] FIG. 6 is a schematic plan view illustrating right and left rotation of a nozzle of a jet propulsion mechanism of a jet propulsion system according to an example embodiment of the present invention.

[0037] FIG. 7 is a schematic side view illustrating upward and downward rotation (trim) of a nozzle of a jet propulsion mechanism according to an example embodiment of the present invention.

[0038] FIG. 8 is a schematic side view illustrating upward and downward rotation of a reverse bucket of a jet propulsion mechanism according to an example embodiment of the present invention.

[0039] FIG. 9 is a partial enlarged view of a portion A in FIG. 2.

[0040] FIG. 10 is a diagram showing a manual operator according to an example embodiment of the present invention from the rear side.

[0041] FIG. 11 is a plan view illustrating movement of a watercraft body during an automatic return and a turning control according to an example embodiment of the present invention.

[0042] FIG. 12 is a flowchart of a control process for an automatic return and a turning control according to an example embodiment of the present invention.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

[0043] Example embodiments of the present invention are hereinafter described with reference to the drawings.

[0044] Jet propulsion watercrafts 100 according to example embodiments of the present invention are now described with reference to FIGS. 1 to 12.

[0045] The jet propulsion watercraft 100 shown in FIGS. 1 and 2 is a personal watercraft, for example, and travels with a relatively small number of people on board. The jet propulsion watercraft 100 is a so-called jet ski or jet bike that glides on the surface of the water. The jet propulsion watercraft 100 includes a watercraft body 110 and a jet propulsion system 120 mounted on the watercraft body 110. The watercraft body 110 includes a hull 111 that defines the bottom of the watercraft, a deck 112 located above the hull 111, and a seat 113 located at the center of the deck 112 in a right-left direction. Furthermore, a reboarding step 116 is provided at a stern 114 of the watercraft body 110, on which a person in the water puts his or her foot when boarding the watercraft body 110. The reboarding step 116 is retractable from the use position shown in FIG. 2 to a predetermined storage position (not shown).

[0046] As shown in FIG. 3, the jet propulsion system 120 includes a communicator 1, a remote control 2, a jet drive source 3, a jet propulsion mechanism 4 including a nozzle 44 (see FIG. 1) to eject a jet of water, an actuator 5 to change the orientation of the jet of water, an operator 6, a lanyard 7, and a controller 8. The actuator 5 includes a steering actuator 50 and a trim actuator 55 to drive the nozzle 44, and a reverse actuator 56 to drive a reverse bucket 45. The remote control 2 is an example of a location information transmitter.

[0047] In the figures, an X direction represents the forward-rearward direction of the jet propulsion watercraft 100. In the X direction, an X1 direction (FRD) represents a forward movement direction, and an X2 direction (BWD) represents a reverse movement direction. In the figures, a Y direction represents the right-left direction of the jet propulsion watercraft 100. In the figures, a Z direction represents the upward-downward direction of the jet propulsion watercraft 100, a Z1 direction represents an upward direction, and a Z2 direction represents a downward direction.

[0048] When a person U has fallen overboard from the watercraft body 110, the jet propulsion system 120 (controller 8) according to an example embodiment of the present invention performs a turning control to point the stern 114 toward the person U (see FIG. 11) who has fallen overboard by ejecting a jet of water from the nozzle 44 and rotating the watercraft body 110 using the steering actuator 50. That is, when the person U has fallen overboard from the watercraft body 110, the jet propulsion system 120 (controller 8) performs a turning control to rotate the watercraft body 110 to point the stern 114 on which the reboarding step 116 is provided toward the person U who has fallen overboard. The details are described below.

[0049] The communicator 1 is provided on the watercraft body 110. The communicator 1 establishes wireless communication with the remote control 2. As an example, the communicator 1 establishes wireless communication with the remote control 2 via Bluetooth (registered trademark). The communicator is not limited to Bluetooth and may be a wireless communicator using other communication standards, such as Wi-Fi (registered trademark). A person on the watercraft causes the remote control 2 to establish wireless communication with the communicator 1 as preparations to travel on the jet propulsion watercraft 100 (see FIG. 4).

[0050] The remote control 2 is held by the person on the jet propulsion watercraft 100. As an example, the remote control 2 is a smartphone. The remote control is not limited to a smartphone and may be a dedicated communication device to wirelessly communicate with the jet propulsion watercraft or a tablet terminal, for example. A dedicated application is installed in the remote control 2 to establish communication with the jet propulsion watercraft 100.

[0051] When the watercraft user (person) of the jet propulsion watercraft 100 has fallen overboard, the remote control 2 is carried by the person U (see FIG. 11) who has fallen overboard. The remote control 2 is able to acquire location information I1 (see FIG. 3) of the remote control 2. Specifically, the remote control 2 includes a GPS receiver. The jet propulsion watercraft 100 also includes a GPS receiver 9. The remote control 2 transmits the location information I1 of the person U (remote control 2) who has fallen overboard to the communicator 1 of the jet propulsion watercraft 100.

[0052] The remote control 2 receives an automatic return instruction to automatically move the watercraft body 110 to a standby position P1 (see FIG. 11) in the vicinity of the person U who has fallen overboard. Execution of the automatic return enables the person U who has fallen overboard to easily reboard the jet propulsion watercraft 100.

[0053] The remote control 2 is a device to instruct movement of the watercraft body 110 by wireless communication with the watercraft body 110. A wireless watercraft maneuvering mode, in which movement of the watercraft body 110 is instructed by the remote control 2, includes the following two modes: a remote watercraft maneuvering mode and an automatic movement mode.

[0054] In the remote watercraft maneuvering mode, the watercraft body 110 is remotely operated using the remote control 2. When remote watercraft maneuvering of mode switching buttons 21 at the upper left of a display screen 20 (see FIG. 5) of the dedicated application of the remote control 2 is selected, the mode switches to the remote watercraft maneuvering mode. When normal of the mode switching buttons 21 is selected, the mode switches to a normal mode in which the watercraft user operates a steering operator 60 to maneuver the jet propulsion watercraft 100. In the remote watercraft maneuvering mode, the jet propulsion watercraft 100 is freely remotely controlled to move using watercraft body operation buttons 22 (such as a forward (F) button, a reverse (R) button, and right and left turn buttons at the center of the screen) on the display screen 20.

[0055] In the automatic movement mode, the watercraft body 110 is automatically moved by remotely instructing the watercraft body 110 to move automatically using the remote control 2. The automatic movement mode includes modes such as the automatic return, fixed point holding, and launching support. When automatic return, fixed point holding, or launching support is selected from the mode switching buttons 21 at the upper left of the display screen 20 (see FIG. 5) of the remote control 2, the mode switches to the automatic movement mode.

[0056] When automatic return is selected on the display screen 20 (see FIG. 5) of the remote control 2 in the automatic movement mode, an automatic return start button 23 (see FIG. 5) is displayed at a lower portion of the display screen 20. When the automatic return start button 23 is operated, an automatic return signal I2 (see FIG. 3) described below is transmitted to the watercraft body 110 to start the automatic return.

[0057] As shown in FIG. 1, the jet drive source 3 includes an engine 30, a crankshaft 31, and a coupling 32. The engine 30 is, for example, a multi-cylinder internal combustion engine. The crankshaft 31 is an output shaft to output a torque generated by the engine 30. The crankshaft 31 extends rearward from the engine 30. The coupling 32 is provided at the rear end of the crankshaft 31 and connects and fixes the crankshaft 31 to an impeller shaft 41 of the jet propulsion mechanism 4.

[0058] As shown in FIG. 2, the jet propulsion mechanism 4 generates a propulsive force by ejecting a jet of water from a jetting port 44a of the nozzle 44. The jet propulsion mechanism 4 includes a water passage 40, the impeller shaft 41, an impeller 42, a nozzle 43 fixed to the rear end of the water passage 40, the nozzle 44 drivably installed on the nozzle 43, and the reverse bucket (reverse gate) 45.

[0059] The water passage 40 extends from a lower portion of the watercraft body 110 toward the stern 114. Water is taken into the water passage 40 through a water intake 40a in the lower portion of the watercraft body 110. The impeller shaft 41 extending rearward is provided in the water passage 40. The impeller 42 is fixed to the impeller shaft 41. The impeller 42 rotates integrally with the impeller shaft 41 to generate a rearward flow. The impeller shaft 41 is connected to the crankshaft 31 via the coupling 32. Therefore, the rotation speed of the impeller 42 increases or decreases as the rotation speed of the engine 30 increases or decreases.

[0060] The nozzle 43 shown in FIG. 6 performs a function to jet the water flowing through the water passage 40 toward the rear nozzle 44. The nozzle 44 is attached to the nozzle 43 from the rear. The nozzle 44 is located at the stern 114 of the watercraft body 110. The nozzle 44 includes the jetting port 44a for a jet of water. The nozzle 44 functions as a deflector to change the orientation of the jet of water ejected from the jetting port 44a. Specifically, the nozzle 44 is attached to the nozzle 43 so as to be rotatable in the right-left direction around a central axis C1 of an upward-downward central shaft 46 extending in the upward-downward direction (the steering position is adjustable around the upward-downward central shaft 46). The central axis C1 is located at the center of the nozzle 44 in the right-left direction. The nozzle 44 is rotated in the right-left direction by the steering actuator 50.

[0061] The nozzle 44 shown in FIG. 7 is attached to the nozzle 43 so as to be rotatable in the upward-downward direction around a central axis C2 of a right-left central shaft 47 extending in the right-left direction (the trim position is adjustable around the right-left central shaft 47). The central axis C2 is located at the center of the nozzle 44 in the upward-downward direction. The nozzle 44 is rotated in the upward-downward direction by the trim actuator 55. Thus, the nozzle 44 is rotated in the upward-downward direction and the right-left direction such that the orientation of the jet of water ejected from the jetting port 44a changes.

[0062] The reverse bucket 45 shown in FIG. 8 changes the orientation of the jet of water in the forward-rearward direction. The reverse bucket 45 rotationally moves between a position above the nozzle 44 and a position behind the nozzle 44. When moved to the position behind the nozzle 44, the reverse bucket 45 covers the jetting port 44a from behind such that the jet of water is directed forward, and the orientation of the jet of water is changed forward. The reverse bucket 45 is rotatable in the upward-downward direction around a central axis C3 of a right-left central shaft 48 extending in the right-left direction. The reverse bucket 45 is rotated in the upward-downward direction by the reverse actuator 56. Depending on the position of the reverse bucket 45, the jet propulsion watercraft 100 switches between a forward movement state, a reverse movement state, and a neutral state in which a forward thrust and a reverse thrust are substantially equal to each other. The jet propulsion watercraft 100 is in the reverse movement or neutral state when the reverse bucket 45 covers the jetting port 44a from behind, and is in the forward movement state when the reverse bucket 45 does not cover the jetting port 44a from behind. The reverse bucket 45 includes, on both the right and left sides thereof, jetting openings 45a each having a substantially cylindrical shape with a central axis directed diagonally forward to the right of the watercraft body 110.

[0063] Referring to FIGS. 2 and 9, the steering actuator 50 includes an electric motor 51 as a drive source, a transmission gear 52 to transmit the drive forces of the electric motor 51 and the steering operator 60 to the nozzle 44, a nozzle-side steering cable 53, and an operator-side steering cable 54. In the wireless watercraft maneuvering mode, the steering actuator 50 uses the drive force of the electric motor 51 to rotate the nozzle 44 in the right-left direction to change the orientation of the jet of water from the jetting port 44a in the right-left direction. The steering actuator 50 is able to rotate the nozzle 44 in the right-left direction even when the jet of water is not being ejected.

[0064] The electric motor 51 includes a motor shaft 51a, a transmission shaft 51b, and a clutch 51c to switch a connection state between the motor shaft 51a and the transmission shaft 51b. The jet propulsion watercraft may not include a clutch. A bevel gear 51d is provided on the side of the transmission shaft 51b opposite to the clutch 51c.

[0065] The transmission gear 52 includes a first gear 52a including a bevel gear 521 to mesh with the bevel gear 51d and a pinion 522, and a second gear 52b including a rack to mesh with the pinion 522. The nozzle-side steering cable 53 includes a first end connected to the transmission gear 52 and a second end connected to the nozzle 44, and pushes and pulls the nozzle 44. The operator-side steering cable 54 includes a first end connected to the transmission gear 52 and a second end connected to the steering operator 60, and pushes and pulls the nozzle 44 via the second gear 52b and the nozzle-side steering cable 53. The nozzle-side steering cable 53 and the operator-side steering cable 54 are push-pull cables. The operator-side steering cable 54 also pushes and pulls the steering operator 60 when the electric motor 51 is driven. That is, when the electric motor 51 is driven, the steering operator 60 operates even when the watercraft user does not operate the steering operator 60. The nozzle-side steering cable 53 is connected to a steering cable connector 44b of the nozzle 44. The nozzle 44 is rotated in the right-left direction by being pushed and pulled by the nozzle-side steering cable 53.

[0066] The trim actuator 55 shown in FIG. 7 includes an electric motor (not shown) as a drive source and a trim cable 55a to transmit the drive force of the electric motor to the nozzle 44. The trim actuator 55 uses the drive force of the electric motor to rotate the nozzle 44 in the upward-downward direction to change the orientation of the jet of water in the upward-downward direction. The trim actuator 55 is able to rotate the nozzle 44 in the upward-downward direction even when the jet of water is not being ejected. The trim cable 55a is connected to a trim cable connector 44c of the nozzle 44. The trim cable 55a is a push-pull cable. The trim actuator 55 is driven based on an operation on a trim operator 62.

[0067] The reverse actuator 56 shown in FIG. 8 includes an electric motor (not shown) as a drive source and a reverse cable 56a to transmit the drive force of the electric motor to the reverse bucket 45. The reverse actuator 56 uses the drive force of the electric motor to rotate the reverse bucket 45 in the upward-downward direction to change the orientation of the jet of water in the forward-rearward direction. The reverse cable 56a is connected to a reverse cable connector 45b of the reverse bucket 45. The reverse cable 56a is a push-pull cable.

[0068] As shown in FIG. 10, the operator 6 includes the steering operator 60, a throttle lever 61, and the trim operator 62.

[0069] The steering operator 60 includes a pair of bar-shaped grips provided on the right and left sides of the watercraft body 110. The drive force input from the watercraft user to the steering operator 60 is transmitted to the nozzle 44 via the operator-side steering cable 54, the transmission gear 52, and the nozzle-side steering cable 53 shown in FIG. 9. Consequently, the nozzle 44 rotates in the right-left direction.

[0070] The throttle lever 61 shown in FIG. 10 increases or decreases the rotation speed of the impeller 42 (opening of a throttle valve of the engine 30) depending on the amount of operation. As the throttle lever 61 is gripped tighter, the amount of operation becomes larger, and thus the force of the jet of water increases. The throttle lever 61 includes a lever position sensor 63 to detect the amount of operation of the throttle lever 61.

[0071] Specifically, the throttle lever 61 includes a forward movement throttle lever 61a to move the watercraft body 110 forward, and a reverse movement throttle lever 61b to move the watercraft body 110 backward. The forward movement throttle lever 61a is provided along the right steering operator 60. The reverse movement throttle lever 61b is provided along the left steering operator 60. The lever position sensor 63 includes a forward movement lever position sensor 63a to detect the amount of operation of the forward movement throttle lever 61a, and a reverse movement lever position sensor 63b to detect the amount of operation of the reverse movement throttle lever 61b.

[0072] The trim operator 62 includes a trim-up button and a trim-down button. When the trim-up button is pressed, the nozzle 44 is rotated upward by the trim actuator 55. When the trim-down button is pressed, the nozzle 44 is rotated downward by the trim actuator 55.

[0073] The lanyard 7 detects that the watercraft user (person) falls overboard. The lanyard 7 includes a switch 70 mounted on the watercraft body 110, a plate 71 removably connected to the switch 70 of the watercraft body 110, and a cord 72. A first end of the cord 72 is held by the watercraft user, and a second end of the cord 72 is connected to the plate 71. When the watercraft user falls overboard, the watercraft user pulls the cord 72, causing the plate 71 to be removed from the switch 70. The controller 8 maintains the drive state of the jet drive source 3 (see FIG. 1) and stops movement of the watercraft body 110 when the plate 71 is removed from the switch 70 of the watercraft body 110.

[0074] That is, the jet propulsion watercraft 100 does not perform an emergency stop of the engine 30 (see FIG. 1) when the plate 71 of the lanyard 7 becomes removed. When the plate 71 of the lanyard 7 becomes removed, the jet propulsion watercraft 100 stops moving with the engine 30 running. The engine 30 is kept running when the plate 71 of the lanyard 7 becomes removed such that the jet propulsion watercraft 100 is able to respond to an automatic return that may be instructed by the person U who has fallen overboard thereafter. A lanyard of a typical jet propulsion watercraft is used as an emergency engine stop switch. Specifically, when a plate of a lanyard of a typical jet propulsion watercraft is removed from a switch, an emergency stop of an engine is performed. In such a case, the engine is not able to be restarted unless the plate is reinserted into the switch.

[0075] As an example, the controller 8 shown in FIG. 1 includes an engine control unit (ECU), a shift control unit (SCU) to control shifting, a remote control unit (RCU) to control maneuvering in the wireless watercraft maneuvering mode, a steering actuator controller to perform a control to drive the steering actuator 50, etc. Alternatively, the controller may include an integrated control unit. The controller 8 includes a computer that includes a CPU, a ROM, a RAM, etc.

[0076] As described above, when a person U has fallen overboard from the watercraft body 110, the controller 8 performs the turning control to point the stern 114 toward the person U who has fallen overboard by ejecting a jet of water from the nozzle 44 and rotating the watercraft body 110 using the steering actuator 50.

[0077] When a person U has fallen overboard from the watercraft body 110, the controller 8 performs the turning control to rotate the watercraft body 110 to point the stern 114 toward the remote control 2 based on the location information I1 (see FIG. 3). When a person U has fallen overboard from the watercraft body 110, the controller 8 executes an automatic return to the standby position P1 based on the automatic return signal I2 (see FIG. 3) instructing the controller 8 to start an automatic return and the location information I1, both of which are received from the remote control 2, and performs the turning control to rotate the watercraft body 110 to point the stern 114 toward the remote control 2 (person U who has fallen overboard) based on the location information I1. The controller 8 performs the turning control while the automatic return is executed. Specifically, the controller 8 performs the turning control while the automatic return is executed or immediately after the automatic return starts.

[0078] During the automatic return, the controller 8 performs the turning control, and then performs a control to move the watercraft body 110 backward to the standby position P1 while pointing the stern 114 toward the remote control 2. Specifically, during the automatic return, the controller 8 moves the watercraft body 110 forward, performs the turning control to point the stern 114 toward the remote control 2 at an intermediate position P2 of the automatic return, and then performs a control to move the watercraft body 110 backward to the standby position P1. During an automatic return, the controller 8 decreases the speed at which the watercraft body 110 is moved backward as compared with the speed at which the watercraft body 110 is moved forward.

[0079] More specifically, when a watercraft body distance D0 from the remote control 2 to the watercraft body 110 is greater than a predetermined distance D2 that is greater than a standby distance D1 from the remote control 2 to the standby position P1 at the time at which the controller 8 receives the automatic return signal I2 from the remote control 2, the controller 8 moves the watercraft body 110 forward to the intermediate position P2 at the predetermined distance D2, and then performs the turning control to point the stern 114 toward the remote control 2. When the watercraft body distance D0 is equal to or less than the predetermined distance D2 at the time at which the controller 8 receives the automatic return signal I2 from the remote control 2, the controller 8 immediately performs the turning control (immediately after the start of the automatic return). The controller 8 also executes the automatic return of the watercraft body 110 to the standby distance D1 along a straight path R linearly connecting the remote control 2 and the watercraft body 110.

[0080] As an example, the predetermined distance D2 is set to a distance of 5 m or more and 15 m or less. As a specific example, the predetermined distance D2 is 10 m. Furthermore, as an example, the standby distance D1 is set to a predetermined distance of 1 m or more and 3 m or less. As a specific example, the standby distance D1 is 1.5 m.

[0081] A control process flow for the automatic return and turning control shown in FIG. 12 is now described with reference to FIG. 11. The automatic return and turning control are executed by the controller 8. The flow described below starts from a state in which a person U has fallen overboard from the watercraft body 110, the jet drive source 3 is maintained in a drive state by the lanyard 7, and movement of the watercraft body 110 has been stopped.

[0082] In step S1, it is determined whether or not the automatic return instruction has been issued. That is, it is determined whether or not the automatic return signal I2 instructing the controller 8 to start the automatic return has been received from the remote control 2. When it is determined that the automatic return instruction has been issued, the process advances to step S2. When it is determined that the automatic return instruction has not been issued, the process operation in step S1 is repeated.

[0083] In step S2, the location information I1 of the person U who has fallen overboard is acquired from the remote control 2. Then, the process advances to step S3.

[0084] In step S3, it is determined whether or not the watercraft body distance D0 is greater than the predetermined distance D2. When it is determined that the watercraft body distance D0 is greater than the predetermined distance D2, the process advances to step S4, and when it is determined that the watercraft body distance D0 is equal to or less than the predetermined distance D2, the process advances to step S6.

[0085] In step S4, the watercraft body 110 is rotated (on the spot) such that the bow 115 is pointed toward the person U who has fallen overboard. In such a case, as a result of the rotation, the remote control 2 is positioned on a central axis of the watercraft body 110 in the right-left direction. At this time, the rotation direction may be either right or left, but it is preferable to rotate in a direction in which the rotation angle is decreased. Then, the process advances to step S5.

[0086] In step S5, the watercraft body 110 is moved straight forward to the intermediate position P2, i.e., to a position at which the watercraft body distance D0 is equal to the predetermined distance D2. At this time, the watercraft body 110 is moved along the straight path R. Then, the process advances to step S6.

[0087] In step S6, the turning control is performed. That is, in step S6, the watercraft body 110 is rotated (on the spot) such that the stern 114 is pointed toward the person U who has fallen overboard. In such a case, as a result of the rotation, the remote control 2 is positioned on the central axis of the watercraft body 110 in the right-left direction. The rotation angle of the watercraft body 110 in step S6 is substantially 180 degrees. Then, the process advances to step S7.

[0088] In step S7, the watercraft body 110 is moved straight backward to the standby position P1 in the vicinity of the person U who has fallen overboard. At this time, the speed of backward movement is slower than the speed of forward movement during the automatic return. Furthermore, at this time, the watercraft body 110 is moved along the straight path R. After being moved to the standby position P1, the watercraft body 110 stops being moved and is held at the standby position P1. Then, the process advances to END.

[0089] According to the various example embodiments of the present invention described above, the following advantageous effects are achieved.

[0090] According to an example embodiment of the present invention, the jet propulsion system 120 includes the controller 8 configured or programmed to, when the person U has fallen overboard from the watercraft body 110, perform the turning control to point the stern 114 toward the person U who has fallen overboard by ejecting a jet of water from the nozzle 44 and rotating the watercraft body 110 using the steering actuator 50. Accordingly, after the person U has fallen overboard, the stern 114 of the watercraft body 110 is pointed toward the person U who has fallen overboard, and thus the person U who has fallen overboard does not need to go around to the stern 114 of the watercraft body 110 when reboarding the watercraft body 110, and the burden on the person U who has fallen overboard is reduced when the person reboards the watercraft body 110. Furthermore, after the person U has fallen overboard, the stern 114 of the watercraft body 110 is pointed toward the person U who has fallen overboard, and thus the person U who has fallen overboard is no longer given an uneasy feeling that the watercraft body 110 is approaching the person from the bow 115 side. Thus, the uneasy feeling experienced by the person U who has fallen overboard from the watercraft body 110 after the person has fallen overboard is reduced. Consequently, the burden on the person U who has fallen overboard is reduced when the person reboards the watercraft body 110, and the uneasy feeling experienced by the person U who has fallen overboard from the watercraft body 110 after the person has fallen overboard is reduced.

[0091] According to an example embodiment of the present invention, the jet propulsion system 120 further includes the communicator 1 on the watercraft body 110, and the location information transmitter (remote control 2) carried by the person U who has fallen overboard to transmit the location information I1 of the person U who has fallen overboard to the communicator 1, and the controller 8 is configured or programmed to, when the person U has fallen overboard from the watercraft body 110, perform the turning control to rotate the watercraft body 110 to point the stern 114 toward the location information transmitter based on the location information I1. Accordingly, the location information transmitter that transmits the location information I1 of the person U who has fallen overboard to the communicator 1 enables the controller 8 to easily identify the location of the person U who has fallen overboard to which the stern 114 should be pointed.

[0092] According to an example embodiment of the present invention, the location information transmitter includes the remote control 2 to receive the automatic return instruction to automatically move the watercraft body 110 to the standby position P1 in the vicinity of the person U who has fallen overboard, and the controller 8 is configured or programmed to, when the person U has fallen overboard from the watercraft body 110, perform the automatic return to the standby position P1 based on the location information I1 and the automatic return signal I2 instructing the controller 8 to start the automatic return, both of which are received from the remote control 2, and perform the turning control to rotate the watercraft body 110 to point the stern 114 toward the remote control 2 based on the location information I1. Accordingly, the stern 114 of the watercraft body 110 is pointed toward the person U who has fallen overboard while the watercraft body 110 is automatically moved to the standby position P1 in the vicinity of the person U who has fallen overboard, and thus the burden on the person U who has fallen overboard is further reduced when the person reboards the watercraft body 110.

[0093] According to an example embodiment of the present invention, the controller 8 is configured or programmed to, during the automatic return, perform the turning control, and then perform a control to move the watercraft body 110 backward to the standby position P1 while pointing the stern 114 toward the remote control 2. Accordingly, the watercraft body 110 is moved backward to reach the standby position P1 in the vicinity of the person U who has fallen overboard, and thus the watercraft body 110 no longer moves toward the person U who has fallen overboard from the bow 115 side in the vicinity of the person U who has fallen overboard. Thus, the uneasy feeling experienced by the person U who has fallen overboard is reduced.

[0094] According to an example embodiment of the present invention, the controller 8 is configured or programmed to, during the automatic return, perform a control to move the watercraft body 110 forward, perform the turning control to point the stern 114 toward the remote control 2 at the intermediate position P2 of the automatic return, and then perform a control to move the watercraft body 110 backward to the standby position P1. Accordingly, up to the intermediate position P2 of the automatic return, the watercraft body 110 is moved forward at a speed relatively faster than a speed at which the watercraft body 110 is moved backward, and thus the time required for the automatic return is reduced as compared with a case in which the watercraft body is moved only backward during the automatic return.

[0095] According to an example embodiment of the present invention, the controller 8 is configured or programmed to, during the automatic return, reduce the speed at which the watercraft body 110 is moved backward as compared with the speed at which the watercraft body 110 is moved forward. Accordingly, the watercraft body 110 is moved backward at a relatively slow speed to reach the standby position P1 in the vicinity of the person U who has fallen overboard, and thus the uneasy feeling experienced by the person U who has fallen overboard is further reduced.

[0096] According to an example embodiment of the present invention, the controller 8 is configured or programmed to move the watercraft body 110 forward to the intermediate position P2 at the predetermined distance D2 that is greater than the standby distance D1 from the remote control 2 to the standby position P1, and then perform the turning control to point the stern 114 toward the remote control 2 when the watercraft body distance D0 from the remote control 2 to the watercraft body 110 is greater than the predetermined distance D2 at the time at which the controller 8 receives the automatic return signal I2 from the remote control 2, and to immediately perform the turning control when the watercraft body distance D0 is equal to or less than the predetermined distance D2 at the time at which the controller 8 receives the automatic return signal I2 from the remote control 2. Accordingly, when the watercraft body 110 is relatively close to the person U who has fallen overboard such that the watercraft body distance D0 is equal to or less than the predetermined distance D2 at the start of the automatic return, the watercraft body 110 is prevented from moving forward toward the person U who has fallen overboard during the automatic return.

[0097] According to an example embodiment of the present invention, the predetermined distance D2 is set to a distance of 5 m or more and 15 m or less. Accordingly, forward movement of the watercraft body 110 is stopped and the watercraft body 110 is switched to backward movement at a location that is relatively far from the person U who has fallen overboard, which is 5 m or more and 15 m or less from the person U.

[0098] According to an example embodiment of the present invention, the standby distance D1 is set to a predetermined distance of 1 m or more and 3 m or less. Accordingly, during the automatic return, the watercraft body 110 is prevented from moving closer to the person U who has fallen overboard than the standby distance D1 of 1 m or more and 3 m or less.

[0099] According to an example embodiment of the present invention, the controller 8 is configured or programmed to perform the automatic return to the standby position P1 of the watercraft body 110 along the straight path R linearly connecting the remote control 2 and the watercraft body 110. Accordingly, an uneasy feeling experienced by the person U who has fallen overboard is reduced.

[0100] According to an example embodiment of the present invention, the jet propulsion system 120 further includes the jet drive source 3 to drive the jet propulsion mechanism 4 to eject a jet of water, and the lanyard 7 including a first end held by the watercraft user and a second end removably connected to the watercraft body 110, and the controller 8 is configured or programmed to maintain the drive state of the jet drive source 3 and stop movement of the watercraft body 110 when the lanyard 7 is removed from the watercraft body 110. Accordingly, even when the lanyard 7 is removed from the watercraft body 110, the drive state of the jet drive source 3 is maintained. That is, a state in which the turning control is able to be performed by the jet drive source 3 is maintained. Furthermore, movement of the watercraft body 110 is stopped, and thus a distance from the person U who has fallen overboard to the watercraft body 110 is prevented from increasing.

[0101] According to an example embodiment of the present invention, the stern 114 of the watercraft body 110 includes the reboarding step 116 to enable the person U who has fallen overboard to put his or her foot thereon when boarding the watercraft body 110, and the controller 8 is configured or programmed to, when the person U has fallen overboard from the watercraft body 110, perform the turning control to rotate the watercraft body 110 to point the stern 114 including the reboarding step 116 toward the person U who has fallen overboard. Accordingly, the reboarding step 116 further reduces the burden on the person U who has fallen overboard when the person reboards the watercraft body 110.

[0102] The example embodiments of the present invention described above are illustrative in all points and not restrictive. The extent of the present invention is not defined by the above description of the example embodiments but by the scope of the claims, and all modifications within the meaning and range equivalent to the scope of the claims are further included.

[0103] For example, while the jet propulsion watercraft is preferably a so-called jet ski or jet bike in example embodiments described above, the present invention is not restricted to this. In an example embodiment of the present invention, the jet propulsion watercraft may alternatively be a so-called jet-propelled sports boat.

[0104] While the jet drive source preferably includes an engine as a drive source to rotate the impeller in example embodiments described above, the present invention is not restricted to this. In an example embodiment of the present invention, the jet drive source may alternatively include an electric motor as a drive source to rotate the impeller.

[0105] While the controller preferably performs the turning control and the automatic return when the watercraft user has fallen overboard in example embodiments described above, the present invention is not restricted to this. In an example embodiment of the present invention, the controller may alternatively perform the turning control and the automatic return when a passenger sitting behind the watercraft user has fallen overboard.

[0106] While the lanyard is preferably used to detect falling overboard in example embodiments described above, the present invention is not restricted to this. In an example embodiment of the present invention, the remote control such as a smartphone held by the person who has fallen overboard may alternatively be used to detect falling overboard. As an example, location information of the remote control such as a smartphone may be used to detect falling overboard when the remote control is spaced apart from the watercraft body by a predetermined distance.

[0107] While the controller preferably performs the automatic return in example embodiments described above, the present invention is not restricted to this. In an example embodiment of the present invention, the controller may not perform the automatic return as long as the controller performs the turning control.

[0108] While the bow is preferably pointed toward the person who has fallen overboard (remote control) at the beginning of the automatic return in example embodiments described above, the present invention is not restricted to this. In an example embodiment of the present invention, the stern may alternatively be constantly pointed toward the person who has fallen overboard (remote control) at the beginning of the automatic return. In other words, the jet propulsion watercraft may alternatively be moved only backward without being moved forward during the automatic return.

[0109] While the speed at which the jet propulsion watercraft is moved backward is preferably slower than the speed at which the jet propulsion watercraft is moved forward during the automatic return in example embodiments described above, the present invention is not restricted to this. In an example embodiment of the present invention, the speed at which the jet propulsion watercraft is moved backward may alternatively be equal to or faster than the speed at which the jet propulsion watercraft is moved forward during the automatic return.

[0110] While the predetermined distance D2 (see FIG. 11) from the remote control 2 (person U who has fallen overboard) to the intermediate position P2 is preferably set to a distance of 5 m or more and 15 m or less in example embodiments described above, the present invention is not restricted to this. In an example embodiment of the present invention, the predetermined distance may alternatively be set to less than 5 m or more than 15 m.

[0111] While the standby distance is preferably set to a predetermined distance of 1 m or more and 3 m or less in example embodiments described above, the present invention is not restricted to this. In an example embodiment of the present invention, the standby distance may alternatively be set to less than 1 m or more than 3 m. Again, the standby distance is smaller than the predetermined distance from the remote control to the intermediate position.

[0112] While the process operations performed by the controller are described using a flowchart in a flow-driven manner in which processes are performed in order along a process flow for the convenience of illustration in example embodiments described above, the present invention is not restricted to this. In an example embodiment of the present invention, the process operations performed by the controller may alternatively be performed in an event-driven manner in which the processes are performed on an event basis. In this case, the process operations performed by the controller may be performed in a complete event-driven manner or in a combination of an event-driven manner and a flow-driven manner.

[0113] While example 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.