Marine propulsion – Jet drive – Direction control for fluid jet
Reexamination Certificate
2000-08-10
2002-01-08
Avila, Stephen (Department: 3617)
Marine propulsion
Jet drive
Direction control for fluid jet
C114S162000
Reexamination Certificate
active
06336834
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates generally to jet-powered watercraft, and more particularly to an auxiliary rudder for the watercraft, which deploys at high speeds when the throttle is shut.
(2) Description of the Prior Art
It is known that the lack of off-throttle steering in jet-powered watercraft, particularly in the one and two person craft typically referred to as Personal Watercraft (PWC). Steering for PWC's is normally provided by aiming the thruster jet nozzle. An experienced driver of such a craft will maintain throttle and steer the craft to avoid a collision. However, in the panic of a high-speed collision avoidance situation, inexperienced drivers have a tendency to let go of the throttle. With the throttle at idle, there is no steerage and the craft proceeds straight, possibly leading to the collision sought to be avoided by letting go of the throttle.
A number of jet-powered watercraft rudder systems for steering at low speeds are available in the prior art. U.S. Pat. No. 3,982,494 to Posti describes an auxiliary rudder coupled to a hydraulic cylinder. The cylinder maintains the rudder within the flow stream of the thruster jet at low speed. At high speed, water pressure from the pump chamber of the thruster operates the cylinder to raise the rudder. In a panic situation as described above, the reaction time of the cylinder to the decreased pressure in the pump chamber would be too long to provide the almost instantaneous rudder deployment required.
U.S. Pat. No. 4,779,553 to Wildhaber, Sr. describes a flat plate rudder pivotally attached to an outboard jet motor, so as to be within the flow of the thruster jet. At slow speeds, the rudder provides steering for the craft. As speed increases, the water force pivots the rudder out of the flow, such that steering is controlled by directing the thruster jet. In a high-speed panic situation, with the throttle cut off, the flow of the thruster jet is stopped. However, the water flow over the rudder from the speed of the craft would maintain the rudder in the raised position.
U.S. Pat. No. 3,976,026 to Eastling provides a steering plate, which is located below the thruster jet flow and is attached to the thruster so as to maintain the same orientation as the flow. The plate is continuously deployed to provide auxiliary steering at all speeds. However, being deployed below the flow subjects the plate to damage from rocks and other obstacles. A spring-loaded mechanism allows the plate to deflect upwards when an obstacle is encountered, so as to mitigate, but not eliminate, damage.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a rudder for high speed steering of a jet-powered watercraft.
Another object of the present invention is to provide a rudder for high speed steering of a jet-powered watercraft, which self-deploys when the watercraft throttle is shut off.
Still another object of the present invention is to provide a rudder for high speed steering of a jet-powered watercraft, which does not protrude below the jet flow during normal operation of the watercraft.
Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings.
In accordance with the present invention, a rudder assembley is pivotally attached to the nozzle of a jet-powered watercraft, so as to turn when the nozzle is turned. At rest, a baffle plate of the assembly partially covers the nozzle and is held in place by a spring at the pivotal attachment point. One or more flat plate rudders are attached perpendicularly to and extend away and down from the baffle plate, parallel with the jet flow from the nozzle. Once the jet begins operating, the force of the water jet against the baffle plate overcomes the spring force and the rudder assembly begins to pivot up and away from the nozzle. At slow running speeds, the force from the jet does not completely overcome the spring force, thus allowing the rudders to be partially within the jet flow and thus contribute to slow speed maneuverability of the watercraft. At high speeds, i.e., at high jet velocities, the jet forces the rudders nearly out of the jet flow and steering is provided by the nozzle direction. The rudders are pivoted up and away from the nozzle so as to prevent damage from underwater obstacles. In an imminent collision situation at high speeds, the panic reaction is to shut off the throttle, which abruptly ends the jet flow from the nozzle. The spring forces the baffle plate back over the nozzle and the rudders are again positioned parallel with the nozzle to provide steering without any flow from the nozzle. Thus the rudder assembly provides a self-deploying, high speed steering capability when the throttle is shut down.
REFERENCES:
patent: 3982494 (1976-09-01), Posti
patent: 4318701 (1982-03-01), Kirkwood
patent: 5642684 (1997-07-01), Aker
patent: 6086437 (2000-07-01), Murray
Nedderman, Jr. William H.
Serth William M.
Avila Stephen
Kasischke James M.
Lall Prithvi C.
McGowan Michael J.
The United States of America as represented by the Secretary of
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