Driving power output control for personal watercraft

1. A jet-propulsion personal watercraft comprising:

a body including a hull and a deck;

an engine mounted to the body;

a driving power output changing system configured to be able to change a driving power output of the engine;

a controller configured to control an operation of the driving power output changing system;

a pressure sensor configured to be able to detect a pressure which is applied to the body from water on which the body is floating, the pressure having a component in a lateral direction of the body;

wherein the controller includes a turning determiner configured to determine whether or not the body is turning in the lateral direction by steering the body, based on a signal received from the pressure sensor; and a driving power output control unit configured to control the driving power output changing system based on information received from the turning determiner;

wherein the controller includes a deceleration determiner configured to determine whether or not the watercraft is decelerating; and

wherein the driving power output control unit is configured to control the driving power output changing system to maintain a propulsion force for turning the body, when the deceleration determiner determines that the watercraft is decelerating and the turning determiner determines that the body is turning.

2. The jet-propulsion personal watercraft according to claim 1 , wherein the driving power output control unit is configured to increase a driving power output of the engine in a case where the turning determiner determines that the body is turning, to maintain the propulsion force for turning the body such that the driving power output is larger than a driving power output of the engine in a case where the turning determiner determines that the body is not turning.

3. A jet-propulsion personal watercraft comprising:

a body including a hull and a deck;

an engine mounted to the body;

a driving power output changing system configured to be able to change a driving power output of the engine;

a controller configured to control an operation of the driving power output changing system; and

a pressure sensor configured to be able to detect a pressure which is applied to the body from water on which the body is floating, the pressure having a component in a lateral direction of the body;

wherein the controller includes a turning determiner configured to determine whether or not the body is turning in the lateral direction by steering the body, based on a signal received from the pressure sensor; and a driving power output control unit configured to control the driving power output changing system based on information received from the turning determiner;

wherein the pressure sensor includes a first pressure sensor which is configured to be able to detect a pressure having a rightward component, and a second pressure sensor which is configured to be able to detect a pressure having a leftward component; and

wherein the turning determiner is configured to determine that the body is turning, when a difference between the pressure detected by the first pressure sensor and the pressure detected by the second pressure sensor is not smaller than a predetermined value.

4. The jet-propulsion personal watercraft according to claim 3 , where the first pressure sensor is disposed to detect a rightward pressure and the second pressure sensor is disposed to detect a leftward pressure.

5. The jet-propulsion personal watercraft according to claim 3 , wherein the first pressure sensor is disposed to detect a pressure in one direction which is substantially perpendicular to a turning direction of the body and the second pressure sensor is configured to detect a pressure in an opposite direction which is substantially opposite to the one direction.

6. The jet-propulsion personal watercraft according to claim 3 , wherein the first pressure sensor is a right pressure sensor attached on a right side of a rear part of the body, and the second pressure sensor is a left pressure sensor attached on a left side of the rear part of the body.

7. The jet-propulsion personal watercraft according to claim 1 ,

wherein the pressure sensor is a single pressure sensor attached on the body; and

wherein the turning determiner determines that the body is turning when the pressure detected by the pressure sensor is outside a reference range.

8. The jet-propulsion personal watercraft according to claim 1 , further comprising:

an engine speed sensor configured to be able to detect an engine speed of the engine;

wherein the driving power output changing system includes an air-intake passage through which air taken in from outside is guided to the engine, an intake valve configured to substantially open and close the air-intake passage, and an intake valve driving device configured to drive the intake valve;

wherein the intake valve is attached with an opening degree sensor configured to be able to detect an opening degree of the intake valve; and

wherein the deceleration determiner determines that the watercraft is decelerating when the engine speed detected by the engine speed sensor is not lower than a predetermined value and the opening degree detected by the opening degree sensor is not larger than a predetermined value.

9. The jet-propulsion personal watercraft according to claim 1 ,

wherein the driving power output changing system includes an air-intake passage through which air taken in from outside is guided to the engine, an intake valve configured to substantially open and close the air-intake passage, and an intake valve driving device configured to drive the intake valve; and

wherein the driving power output control unit is configured to execute valve opening degree control for causing the intake valve driving device to control an opening degree of the intake valve to maintain a propulsion force for turning the body, when the deceleration determiner determines that the watercraft is decelerating, and the turning determiner determines that the watercraft is turning.

10. The jet-propulsion personal watercraft according to claim 9 ,

wherein the air-intake valve includes a throttle valve configured to substantially open and close the air-intake passage according to an amount of a driver's operation, and a bypass valve configured to substantially open and close a bypass passage connected to the air-intake passage so as to bypass the throttle valve;

wherein the intake valve driving device is a bypass valve driving device configured to drive the bypass valve; and

wherein the driving power output control unit is configured to execute valve opening degree control for causing the bypass valve driving device to increase or maintain an opening degree of the bypass valve, when the deceleration determiner determines that the watercraft is decelerating and the turning determiner determines that the watercraft is turning.

11. The jet-propulsion personal watercraft according to claim 1 ,

wherein the driving power output changing system includes an ignition device configured to ignite an air-fuel mixture in the engine; and

wherein the driving power output control unit is configured to execute ignition timing control for increasing an advancement angle value of ignition timing of the ignition device, when the deceleration determiner determines that the watercraft is decelerating and the turning determiner determines that the watercraft is turning.