Patent Application
20250206431
This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2023-216622, filed Dec. 22, 2023, the entire contents of which are incorporated herein by reference.
The present invention relates to personal watercraft such as a water motorcycle and a small outboard motor and a controlling method of the same.
Examples of personal watercrafts (abbreviated to PWC) include small boats also called water motorcycles or jet-propelled boats. Especially, personal watercrafts that are propelled by jet thrust are capable of not only traveling at high speed but also turning at small turning radii and changing their speed quickly. Thus, the personal watercrafts are excellent in their mobility and agility and thus are expected to be useful in various situations. For example, in the field of water-based leisure activities, the personal watercrafts can be not only operated in a normal driving but also maneuvered in acrobatic manners.
In this specification, the term “turn” is a concept that includes not only changes in courses that change the direction of a hull by nearly 180 degrees such as a U-turn but also changes in courses at other angles. For example, a full turn at angles more than 360 degrees or a turn at an angle less than 360 degrees or at an obtuse angle less than or equal to 90 degrees are included as well. That is, in this specification, a turn means changes in courses that may cause skidding.
Turns of the personal watercraft at the high speed may cause skidding. The factors that cause skidding are not limited to boat speed and turning radii. For example, sea conditions such as waves, wind, and currents can be factors as well. Therefore, a certain boat speed and turning radii may cause skidding or may not cause skidding depending on sea conditions. Once skidding occurs, a hull may face an unintended direction, spin, or fail to turn a curve properly and thus make a wide turn on the curve. In addition, skidding may cause operators to lose their posture or change the hull's posture significantly.
In order to stabilize the posture of the hull in traveling, small boats having additional configurations such as a configuration in which a sponson is attached to a side of the hull and a configuration in which a trim tab is controlled are known. These small boats having additional configurations can travel in a stable manner but also suppress agile turns. It is possible to some degrees to find a compromise between the stability and the turning capability by changing the size and shape of sponsons. However, it is difficult to use such additional configurations flexibly according to the purpose of the use and sea conditions.
The small boat described in JP H9-86484 A (Patent Literature 1) has a means of suppressing skidding in a turn. The small boat controls the exhaust duct for jet thrust according to the amount of rotations of the steering device. For example, the control valve is provided in the exhaust duct. This control valve is operated by the valve driving means operating in association with the steering device.
The small boat described in JP 2021-75133 A (Patent Literature 2) detects the engine speed or the opening degree of the throttle and controls the trim angle based on the detected signal. For example, at the start of a turn, the trim actuator activates the deflector to reduce the trim angle of the hull, thereby suppressing an increase in the turning radii.
The jet-propelled boat described in U.S. Pat. No. 9,623,943 B2 (Patent Literature 3) includes the turning state determination section for determining the turning state of the hull. The turning state determination section detects the turning state of the hull based on the operation angle of the steering member, the traveling speed, the engine speed, and the like. When the turning state is determined to be the turning state of the high-speed traveling, the engine speed is reduced.
These conventional small boats described in Patent Literatures 1, 2, 3, and the like predict the occurrence of skidding based on data such as the operation angle of the steering device, the engine speed, the boat speed, and the like. However, the occurrence of skidding depends on sea conditions such as waves, wind, and currents. For example, skidding occurs in some cases depending on conditions of waves and wind hitting the hall in a turn.
Therefore, even when skidding is predicted based on the operation angle of the steering device, the engine speed, the boat speed, and the like, a failure to address ever-changing sea conditions may lead to unexpected skidding. However, when a control that uniformly suppresses skidding regardless of the skill of the operator or the sea conditions is performed, the boat speed in a turn is decreased more than necessary and thus the turning radii becomes larger. Such a control is not preferable.
Other conventional examples include small boats including capsizing sensors. When a small boat including a capsizing sensor loses control of its hull due to skidding and the like, the capsizing sensor that has detected capsizing outputs a signal to stop the engine in this capsized state. However, even the capsizing sensor cannot suppress skidding itself.
The embodiments of the present invention aim to provide the personal watercrafts capable of suppressing skidding, which is caused at the time of operating the steering, without suppressing boat speed in a turn more than necessary and the control method of the same.
One embodiment is a personal watercraft comprising a hull, an engine mounted on the hull, a fuel supply mechanism such as a throttle mechanism for controlling a rotation of the engine, and a steering device for steering. The fuel supply mechanism may be a fuel injection system comprising a fuel injection valve, a fuel injection pump, and the like. Furthermore, the personal watercraft comprises a detection unit and a control unit. The detection unit includes a sensor detecting at least one of an angular velocity and an angular acceleration around a yaw axis of the hull. The control unit performs a deceleration control of the engine when the angular velocity or the angular acceleration around the yaw axis detected by the detection unit exceeds each threshold value in a turn of the hull. The threshold value of the angular velocity and the threshold value of the angular acceleration are different from each other.
In the personal watercraft of the present embodiment, in a turn of the hull in a direction, the control unit performs a first-time deceleration control based on the angular acceleration. Further, in the turn of the hull in the same direction as the first-time deceleration control, second-and-subsequent deceleration controls may be performed based on the angular velocity. The detection unit may include an inertial measurement unit (IMU). This inertial measurement unit detects an angular velocity and an angular acceleration in a role direction, an angular velocity and an angular acceleration in a pitch direction, and an angular velocity and an angular acceleration around a yaw axis. The control unit may perform the deceleration control based on at least one of the angular velocity and the angular acceleration around the yaw axis.
A controlling method of a personal watercraft of an embodiment of the present invention detects at least one of the angular velocity and the angular acceleration around the yaw axis with the hull turning, and when a detected angular velocity or a detected angular acceleration exceeds each threshold value, performs a deceleration control to decelerate the engine.
In the control method of the embodiment, the angular velocity and the angular acceleration around the yaw axis of the hull are detected. In a turn of the hull in a direction, a first-time deceleration control is then performed based on the angular acceleration. Furthermore, in the turn of the hull in the same direction as the first-time deceleration control, second-and-subsequent deceleration controls may be performed based on the angular velocity.
The personal watercraft and the control method of the present invention can suppress skidding that occurs in a turn and prevent the boat speed in a turn from being reduced more than necessary.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.
The following describes a personal watercraft and a controlling method of the same of the first embodiment with reference to
The personal watercraft 10 of the present
embodiment includes: a hull 11; an engine 12 mounted on the hull 11; a steering device 13 for steering; a water jetting nozzle 14; a control unit (a controller) 15; a throttle mechanism 16; a detection unit 21 including an inertial measurement unit (IMU) 20; and the like. The water jetting nozzle 14 is arranged at the rear of the hull 11. The control unit 15 includes electrical circuits for controlling the engine 12. The throttle mechanism 16 is an example of a fuel supply mechanism. Other examples of the fuel supply mechanism include fuel injection systems comprising fuel injection valves, fuel injection pumps, and the like.
The rotation of an impeller by the engine 12 makes the water jetting nozzle 14 jet water flow, which is for jet thrust, into water. The throttle mechanism 16 controls the rotation of the engine 12. In other words, when the opening degree of the throttle mechanism 16 (referred to as a throttle opening degree as well) is large, the engine 12 rotates at high speed, and when the throttle opening degree is small, the engine 12 rotates at low speed. In a case of an engine using the fuel injection valve, the engine 12 rotates at low speed by reducing the amount of injected fuel. As an example of the engine deceleration control, the fuel cut or the ignition cut may be adopted.
The steering device 13 includes a steering member 13a and a steering cable 30. The steering cable 30 transmits the movement of the steering member 13a to the water jetting nozzle 14. When the steering member 13a is turned to the right or left, the direction of the water jetting nozzle 14 is changed via the steering cable 30. This can change the direction of the hull 11. The operation direction and the operation angle of the steering member 13a are detected by a steering sensor 31 (shown in
The steering member 13a includes an accelerator control unit 32 for operating the accelerator and an accelerator sensor 33. When the accelerator control unit 32 is manually operated, a signal to control the opening degree of the accelerator is output from the accelerator sensor 33 to the control unit 15 according to the amount of this manual operation. The control unit 15 changes the opening degree of the accelerator of the throttle mechanism 16 based on this accelerator control signal.
The detection unit 21 includes the inertial measurement unit 20. As shown in
The X-axis of the inertial measurement unit 20 extends in the fore-and-aft direction of the hull 11. In other words, the rotation around the X-axis is the direction along which the hull 11 rolls (a roll direction). The Y-axis extends in the width direction of the hull 11. The rotation around the Y-axis is the direction along which the hull 11 pitches (a pitch direction). The Z-axis extends in the vertical direction of the hull 11. The rotation around the Z-axis is a yaw direction of the hull 11. In this specification, a rotation in the yaw direction is referred to as a rotation around the yaw axis in some cases.
Next, an example of the method of controlling the personal watercraft 10 of the present embodiment will be described with reference to
In a step ST1 in
For example, turning the steering member 13a to the right as shown by R1 in (1) [Steering] in
In a step ST3 in
When the angular acceleration does not exceed the first threshold value TH1 (“NO” in the step ST4), the process proceeds to a step ST5. In the step ST5, it is determined whether or not the angular velocity exceeds a second threshold value TH2. When the angular velocity exceeds the second threshold value TH2 (“YES” in the step ST5), the process proceeds to the step ST6. In the step ST6, the deceleration control of the engine 12 is performed by the control unit 15 outputting a signal to reduce the opening degree of the throttle to the engine 12. The first threshold value TH1 of the angular acceleration and the second threshold value TH2 of the angular velocity are different from each other.
In the step ST6, for example, the deceleration control to reduce the opening degree of the throttle to be close to zero is performed, as shown in (4) [Opening Degree of Accelerator] in
In a step ST8 in
As indicated by L1 in (1) [Steering] in
Once skidding occurs and thus the hull's posture becomes unstable, addressing skidding is difficult in some cases. The inventors of the present invention therefore focused on that the rise in the angular acceleration is faster than the rise in the angular velocity at the start of skidding. In other words, in the step ST4, the rise in the angular acceleration at the start of skidding is detected. Then, when the angular acceleration exceeds the first threshold value TH1, the process proceeds to the deceleration control to be performed in the step ST6 and the subsequent steps. This configuration allows the deceleration control to start before skidding becoming large. However, depending on situations, the process may proceed to the deceleration control in the step ST6 based on the magnitude of the angular velocity, as shown in the step ST5. The control unit of the present embodiment performs the deceleration control of the engine when the angular velocity or the angular acceleration around the yaw axis detected by the detection unit in a turning of the hull exceeds the respective threshold values. That is, the deceleration control of the engine is performed when the angular acceleration exceeds the first threshold value or the angular velocity exceeds the second threshold value. The first threshold value and the second threshold value are different from each other.
For reference, a comparative example shown in
example examined by the present inventors in the course of developing the personal watercraft. The personal watercraft of the comparative example also includes the inertial measurement unit and detects the angular velocity and the angular acceleration. However, the personal watercraft of the comparative example does not perform the skidding suppression processing described in the first embodiment. This comparative example was examined in private and thus is not publicly known.
Items (1) to (5) in
As shown by R1 in (1) [Steering] in
In (4) [Opening Degree of Accelerator] in
The following describes a controlling method of a personal watercraft of the second embodiment with reference to
Line Segment B [Angular Velocity] in
Line Segment D [Opening Degree of Accelerator] in
In a step ST10 in
For example, as shown by R2 in Line Segment A [Steering] in
In a step ST12 in
In the step ST13, when the angular acceleration does not exceed the first threshold value TH1 (“NO” in the step ST13), the process proceeds to a step ST15. In the step ST15, it is determined whether or not the angular velocity exceeds a second threshold value TH2. When the angular velocity exceeds the second threshold value TH2 (“YES” in the step ST15), the process proceeds to the step ST16, and then the deceleration control is performed.
In the step ST16, for example, the
deceleration control to make the opening degree of the throttle close to zero is performed, as shown in Line Segment D [Opening Degree of Accelerator] in
In a step ST18 in
In the example shown in
When it is determined that the steering member 13a is returned to the neutral position in the step ST18 in
For example, when the steering member is operated to the left as shown in L2 in Line Segment A [Steering] in
In this manner, with respect to the skidding suppression processing in the second embodiment, the first-time deceleration control in the turn in a direction proceeds to the step ST16, and the deceleration control based on the angular acceleration is performed. This enables decreasing thrust at the start of skidding and thus effectively suppressing skidding. In the second-and-subsequent deceleration controls, the boat speed has been already reduced to some degrees due to the first-time deceleration control. Thus, the process proceeds to the step ST15 and the deceleration control based on the angular velocity is performed.
When the waveform of Line Segment B [Angular Velocity] and Line Segment C [Angular Acceleration] shown in
Therefore, in the skidding suppression processing in the second embodiment in the turn in the same direction, the first-time deceleration control is performed based on the angular acceleration, and the second-and-subsequent deceleration controls are performed based on the angular velocity. This prevents the engine speed from changing more than necessary in the turn. Further, the deceleration control can be performed at the early stage of skidding.
In a personal watercraft comprising an inertial measurement unit 20, at least one of the angular velocity and the angular acceleration around the X-axis (the roll direction) may be detected to be used in the skidding suppression processing. For example, in the skidding suppression processing described in the second embodiment, information on the angular velocity or the angular acceleration in the roll direction may be considered. Alternatively, the angular velocity and the angular acceleration around the Y-axis (the pitch direction) may be detected to be used in the skidding suppression processing.
In addition to the information on the roll and the pitch of the hull, the velocity of the hull may be detected to be used for the skidding suppression processing (a trigger for the deceleration control). In addition, the combination of information on these items (the roll, the pitch, and the velocity of the hull), the angular velocity, and the angular acceleration may be used to perform the skidding suppression processing. For example, a threshold value of the angular acceleration (the first threshold value TH1) and a threshold value of the angular velocity (the second threshold value TH2) may be changed according to information on the pitch, the roll, and the velocity of the hull, for example.
The personal watercraft comprising a sponson for stabilizing the hull may adopt a movable sponson. In that case, overhang amount of the sponson may be changed to suppress skidding according to the magnitude of the angular velocity or the angular acceleration detected by the inertial measurement unit and the like in a turn.
Personal watercrafts comprising movable trim tabs are also known. In the personal watercrafts comprising the movable trim tabs, a tilt angle of the trim tabs may be varied to suppress skidding according to the magnitude of the angular velocity or the angular acceleration detected by the inertial measurement unit and the like in a turn.
In implementing the present invention, the detection unit is not limited to the inertial measurement unit and may be a sensor that can detect at least the angular velocity and the angular acceleration in the yaw direction. It goes without saying that the constituent elements of the personal watercraft such as the hull, the engine, and the steering device can also be changed as necessary. The skidding suppression processing for the present invention may be adopted in the outboard motors.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-216622 | Dec 2023 | JP | national |
