Marine propulsion – Jet drive – Direction control for fluid jet
Reexamination Certificate
1999-06-11
2001-07-31
Swinehart, Ed (Department: 3617)
Marine propulsion
Jet drive
Direction control for fluid jet
Reexamination Certificate
active
06267633
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a jet propulsion unit for a watercraft, and more particularly to a reverse thrust deflector assembly.
2. Description of Related Art
Personal watercraft have become very popular in recent years. This type of watercraft is quite sporting in nature and carries a rider and possibly one or two passengers. A relatively small hull of the personal watercraft commonly defines a riders' area above an engine compartment. An internal combustion engine frequently powers a jet propulsion unit which propels the watercraft. The engine lies within the engine compartment in front of a tunnel formed on the underside of the watercraft hull. The jet propulsion unit is located within the tunnel and is driven by an output shaft of the engine. In particular, an impeller shaft of the jet propulsion unit extends forward, through a wall of the hull tunnel, and is coupled to the engine output shaft. In this manner, the engine drives the jet propulsion unit.
The jet propulsion unit conventionally includes an impeller housing in which an impeller is contained. The impeller, which is driven by the engine through the impeller shaft, draws water through a water inlet and forces it through a discharge nozzle to propel the watercraft. A steering nozzle usually is mounted on the discharge nozzle for pivotal movement about a vertical axis. Pivotal movement of the steering nozzle about the vertical steering axis alters a discharge direction of the water jet to steer the watercraft.
Many personal watercraft also include a reverse thrust deflector to issue water forwardly and produce a reverse thrust. A pair of support arms typically support the reverse thrust deflector about the end of the jet propulsion unit. These arms usually are pivotally mounted onto the discharge nozzle or onto a ride plate that extends beneath at least a portion of the jet propulsion unit. The pivotal movement of the arms moves the reverse thrust deflector from a raised position, in which the deflector does not affect the water jet issuing from the steering nozzle, and a fully lowered position, in which the deflector cooperates with the steering nozzle and redirects water issuing from the jet propulsion unit forwardly to achieve a reverse thrust. In some prior watercraft, the reverse thrust deflector also assumes an intermediate position which corresponds to a neutral position.
Both the steering nozzle and the reverse thrust deflector are pivotally supported and are operated remotely. As such, each requires separate actuation mechanisms that must not interfere with each other. That is, the mechanism for actuating the reverse thrust deflector, which pivots about a horizontally disposed axis, must not interfere with the mechanism that affects the steering of the watercraft. For this reason, first and second flexible wire actuators usually are employed to operate the steering nozzle and the reverse thrust deflector, respectively. The layout of these components and actuators though typically is complicated owing to the tight confined area of the tunnel in which the components and actuators are disposed.
Prior the buckets are also prone to bouncing up and down when the watercraft is operated in reverse with the thrust bucket in the lowered position. The thrust bucket under some conditions or after repeated use may become worn and tend to rattle and move about when raised.
SUMMARY OF THE INVENTION
A need therefore exists for a reverse thrust deflector assembly which prevents the deflector from bouncing when in a lowered position and prevents the deflector from falling when in the raised position. The reverse thrust deflector assembly also desirably provides a compact support assembly for the thrust deflector and improves the arrangement of various components used with the thrust deflector and the propulsion system.
An aspect of the present invention involves a jet propulsion unit for a watercraft that comprises an impeller disposed within a housing assembly. A nozzle is arranged downstream of the impeller and a thrust deflector is pivotally supported relative to the nozzle and movable between a first position and a second position. The rust deflector is disposed relative to the nozzle so as to redirect at least a portion of the water stream issuing from the nozzle when the thrust deflector is moved into the second position. First and second stops are provided which cooperate with the thrust deflector to define the first and second positions. A releasable locking mechanism is attached to the thrust deflector, and engages the first stop or the second stop when the rust deflector is positioned in the first position or the second position, respectively. A lost motion connection operates between the thrust deflector and the locking mechanism so as to release the locking mechanism from one of the stops to move the thrust deflector from at least one of the positions.
The jet propulsion unit desirably is combined with a personal watercraft that includes a hull defining a rider's area and an engine compartment. An engine is disposed within the engine compartment and includes an output shaft. The jet propulsion unit is coupled to the engine output shaft In one variation, a remote operator is disposed near the rider's area and is coupled to the thrust deflector by an actuator mechanism to move the thrust deflector between the first and second positions.
In an additional variation, the nozzle is rotatable between a fully trimmed-up position and a fully tried-down position. In the fully trimmed-down position, a central axis of the nozzle is skewed at a discharge angle relative to a central axis of the jet propulsion unit. The thrust deflector includes at least one inclined, laterally extending rib that is positioned on a side of the thrust deflector that faces the nozzle, and is oriented at an inclined angle relative to the central axis of the jet propulsion unit. The inclined angle of the rib is larger than the discharge angle of the nozzle when fully trimmed down so as to guide at least portion of the water issuing from the nozzle even when the nozzle is in the fully trimmed-down position.
Another aspect of the present invention involves a bracket assembly that supports the thrust deflector about a jet propulsion unit which includes a discharge nozzle and a steering nozzle. The discharge nozzle and the steering nozzle are arranged downstream of the impeller and in series such that the steering nozzle receives water issuing from the discharge nozzle. The bracket assembly includes a pair of arms that are attached to the discharge nozzle. The arms extend at least toward the steering nozzle, and the thrust deflector is pivotally coupled to the arms. In one mode, the thrust deflector is pivotally coupled to the arms at a point near an effluent end of the discharge nozzle. In an additional variation, the arms of the bracket assembly extend along at least a portion of the sides of the steering nozzle.
At least one of the arms desirably defines a hollow space extending alongside the jet propulsion unit. An actuator, which is coupled to the steering nozzle, is disposed within this hollow space. In addition, additional actuators and/or conduits can also be disposed in this space.
Further aspects, features, and advantages of the present invention will become apparent from the detailed description of the preferred embodiments which follows.
REFERENCES:
patent: 4026235 (1977-05-01), Woodfill
patent: 4813895 (1989-03-01), Takahashi
patent: 5154640 (1992-10-01), Nakase
patent: 5304078 (1994-04-01), Kaneko
patent: 5350325 (1994-09-01), Nanami
patent: 5494464 (1996-02-01), Kobayashi et al.
patent: 5551898 (1996-09-01), Matsumoto
patent: 5752864 (1998-05-01), Jones et al.
patent: 2-29892 (1990-02-01), None
patent: 0065492 (1991-03-01), None
Knobbe Martens Olson & Bear LLP
Swinehart Ed
Yamaha Hatsudoki Kabushiki Kaisha
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