Marine propulsion – Means to control the supply of energy responsive to a sensed...
Reexamination Certificate
2001-08-02
2003-07-08
Swinehart, Ed (Department: 3617)
Marine propulsion
Means to control the supply of energy responsive to a sensed...
C440S087000
Reexamination Certificate
active
06589085
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a jet-propulsion watercraft which ejects water rearward and planes on a water surface as the resulting reaction. More particularly, the present invention relates to a jet-propulsion watercraft that can maintain steering capability even when the throttle is operated in the closed position and propulsion force is thereby reduced.
2. Description of the Related Art
In recent years, so-called jet-propulsion personal watercraft (PWC) have been widely used in leisure, sport, rescue activities, and the like. The personal watercraft is configured to have a water jet pump that pressurizes and accelerates water sucked from a water intake generally provided on a bottom of a hull and ejects it rearward from an outlet port. Thereby, the personal watercraft is propelled.
In the personal watercraft, in association with a steering handle of a general bar type, a steering nozzle provided behind the outlet port of the water jet pump is swung either to the right or left, to change the ejecting direction of the water to the right or to the left, thereby turning the watercraft.
A deflector is retractably provided behind the steering nozzle for blocking the water ejected from the steering nozzle. The deflector is moved downward to deflect the ejected water forward, and as the resulting reaction, the personal watercraft moves rearward. In some watercraft, in order to move rearward, a water flow is formed so as to flow from an opening provided laterally of the deflector along a transom board to reduce the water pressure in an area behind the watercraft.
In the above-described personal watercraft, when the throttle is moved to a substantially fully closed position and the water ejected from the water jet pump is thereby reduced, during forward movement and rearward movement, the propulsion force necessary for turning the watercraft is correspondingly reduced, and the steering capability of the watercraft is therefore reduced until the throttle is re-opened.
To solve the above-described condition with a mechanical structure, the applicant disclosed a jet-propulsion personal watercraft comprising a steering component for an auxiliary steering system which operates in association with the steering handle in addition to a steering nozzle for the main steering system in Japanese Patent Application No. Hei. 2000-6708.
Also, for the purpose of achieving a lightweight watercraft, the applicant disclosed a jet-propulsion personal watercraft in Japanese Patent Application No. Hei. 2000-173232, in which a sensor is adapted to detect a throttle-close operation, a steering operation, or the like, and an engine speed is increased according to the detection.
SUMMARY OF THE INVENTION
The present invention addresses the above-described condition, and an object of the present invention is to provide a jet-propulsion watercraft, which can maintain steering capability according to the cruising speed thereof even while an operation which closes the throttle is performed and the amount of water ejected from a water jet pump is thereby reduced. More specifically, the watercraft is adapted to execute a control for increasing the engine speed while the throttle-close operation and the steering handle operation are detected. The engine speed increase is controlled so that the rate of change upon the control is subdued making the watercraft continue to turn smoothly.
According to the present invention, there is provided a jet-propulsion watercraft comprising: a water jet pump that pressurizes and accelerates sucked water and ejects the water from an outlet port provided behind the water jet pump to propel the watercraft as a reaction of the ejecting water; an engine for driving the water jet pump; a steering operation means that operates in association with a steering nozzle of the water jet pump; a steering position sensor for detecting a predetermined steering position of the steering operation means; a throttle-close operation sensor for detecting a throttle-close operation; a cruising speed obtaining means for obtaining a cruising speed of the watercraft; and an electric control unit, wherein the electric control unit is adapted to increase the engine speed to a predetermined engine speed during the detection of the predetermined steering position by the steering position sensor and the detection of the throttle-close operation by the throttle-close operation sensor while changing an increasing speed of the engine speed according to the cruising speed obtained by the cruising speed obtaining means.
According to the jet-propulsion watercraft of the present invention, the engine speed is increased to the predetermined engine speed while the watercraft is steered, this operation is detected by the steering position sensor, and while the throttle-close operation is detected by the throttle-close operation sensor. Therefore, the water sufficient to turn the watercraft is ejected from the water jet pump, and the steering capability can be maintained even while the throttle-close operation is performed. Also, since the increasing speed of the engine speed is changed according to the cruising speed obtained by the cruising speed obtaining means, the ejected water amount adapted to the cruising speed can be obtained, and the rider is given improved steering feeling.
Herein, control for increasing the engine speed is referred to as “steering assist mode control”, and the “throttle-close operation” means that operation is performed to bring the throttle toward a closed position by a predetermined amount or more.
It should be noted that the throttle-close operation sensor of the present invention is not limited to the engine speed sensor and the throttle position sensor. For example, it is possible to use a sensor placed in a system connecting a throttle lever and a throttle valve for detecting an operation of the system while the throttle-close operation is performed. Also, it is possible to use a sensor for detecting an air-intake pressure and an air-intake amount of the engine.
Under the steering assist mode control, the engine speed can be increased by changing at least any of the fuel injection timing of the fuel injection system of the engine, the ignition timing of an ignition system of the engine, and the fuel injection amount of the fuel injection system of the engine. In this case, the engine speed can be increased without actual operation of the throttle.
In the jet-propulsion watercraft, the speed for increasing the engine speed to the predetermined engine speed according to the change in the cruising speed may be changed stepwise.
It is preferable that in the jet-propulsion watercraft, smaller increasing speeds of the engine speed are set for higher cruising speeds. Thereby, the change in the cruising speed occurring in transition to the steering assist mode control can be subdued, and the steering feeling under the control is improved.
In the jet-propulsion watercraft, a cruising speed sensor for detecting the cruising speed of the watercraft may be used as the cruising speed obtaining means. Also, the cruising speed may be calculated from the engine speed.
The jet-propulsion watercraft may further comprise: an increasing speed table that prestores an increasing speed of the engine speed according to the cruising speed. The increasing speed according to the cruising speed obtained by the cruising speed obtaining means may be read from the increasing speed table and the engine speed may be increased to the predetermined engine speed based on the increasing speed read from the increasing speed table. Thereby, the control for changing the increasing speed of the engine speed can be more simply executed. To obtain the stored increasing speeds of the engine speed that give preferable steering feeling, the engine speeds associated with a variety of actual cruising speeds are experimentally increased to the predetermined engine speed.
The increasing speed table may be adapted to divide a predetermined cruising speed range into a plurality of s
Maeda Kiyoaki
Matsuda Yoshimoto
Kawasaki Jukogyo Kabushiki Kaisha
Marshall Gerstein & Borun
Swinehart Ed
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