Ships – Motorized self-propelled waterski or waterscooter-type vehicle – Having pivoted steering and towing mast for rider
Reexamination Certificate
2002-07-16
2004-01-13
Sotelo, Jesus D. (Department: 3617)
Ships
Motorized self-propelled waterski or waterscooter-type vehicle
Having pivoted steering and towing mast for rider
C440S038000, C440S043000
Reexamination Certificate
active
06675730
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to jet powered watercraft, especially personal watercraft (“PWC”). More specifically, the invention concerns control systems that assist in maneuvering jet powered watercraft when the jet pump fails to produce sufficient thrust to assist in directional control of the watercraft. In particular, the invention is directed to steering assistance for a PWC.
2. Description of Related Art
Jet powered watercraft have become very popular in recent years for recreational use and for use as transportation in coastal communities. The jet power offers high performance, which improves acceleration, handling, and shallow water operation. Accordingly, PWCs, which typically employ jet propulsion, have become common place, especially in resort areas.
As use of PWCs has increased, the desire for better performance and enhanced maneuverability has become strong. Operators need to be able to handle the watercraft in heavily populated areas, especially to avoid obstacles, other watercraft and swimmers. Also, as more people use PWCs as a mode of transportation, it is also preferred that the craft be easily docked and maneuvered in public places.
Typically, jet powered watercraft have a jet pump mounted within the hull that takes in water and expels the water at a high thrust to propel the watercraft. Most PWCs operate with this system. To control the direction of the watercraft, a nozzle is generally provided at the outlet of the jet pump to direct the thrust, or flow of pressurized water, in a desired direction. Turning is achieved by redirecting the thrust. In conventional, commercially available PWCs, the only mechanism provided for turning is the nozzle.
The nozzle is mounted on the rear of the craft and pivots such that the thrust may be selectively directed toward the port and starboard sides within a predetermined range of motion. The direction of the nozzle is controlled from the helm of the watercraft by the person operating the craft. By this, the operator can steer the watercraft in a desired direction. For example, when a PWC operator chooses to make a starboard-side turn, he or she turns the helm clockwise. This causes the nozzle to be directed to the starboard side of the PWC so that the thrust will effect a starboard turn.
During operation, when the user stops applying the throttle, the motor speed (measured in revolutions per minute or RPMs) drops, thus slowing or stopping the flow of water through the nozzle at the rear of the watercraft. This results in reducing the thrust generated by the pump. Accordingly, the water pressure in the nozzle drops. This is known as an “off-throttle” situation. This can occur at low vehicle speeds, for example when the operator is approaching shore or a dock, or at high vehicle speeds, when the operator releases the throttle.
Thrust will also be reduced if the user stops the engine by pulling the safety lanyard or pressing the engine kill switch. The same condition occurs in cases of engine failure (i.e., no fuel, ignition problems, etc.) and jet pump failure (i.e., rotor or intake jam, cavitation, etc.). These are known as “off-power” situations. For simplicity, throughout this application, the term “off-power” will also include “off-throttle” situations, since both situations have the same effect of reducing pump pressure and thus reducing thrust.
Since the flow of pressurized water is the thrust that causes the vehicle to turn, when the thrust is reduced or eliminated, steering becomes less effective. As a result, a need has developed to improve the steerability of PWCs under circumstances of insufficient thrust when the pressure generated by the pump has decreased below a predetermined threshold. This is particularly significant when docking or when driving through low wake areas. This is also important when the vehicle is operating at high speeds and the throttle is released, which would create a situation where steering assistance is needed.
One example of a prior art system is shown in U.S. Pat. No. 3,159,134 to Winnen, which provides a system where steering assistance is provided by vertical flaps positioned at the rear of the watercraft on either side of the hull. In this system, when travelling at low speeds, the thrust from the propulsion system provides minimal steering for the watercraft. When the operator turns the helm, one of the side flaps pivots outwardly from the hull into the flow of water with a flap bar to improve steering control. However, this system is not advantageous for several reasons discussed below.
A system similar to Winnen is schematically represented by
FIG. 18
, which shows a watercraft
1100
having a helm
114
. Flaps
1116
a
,
1116
b
are attached to the sides of the hull via a flap bar
1128
a
,
1128
b
at a front edge. Two telescoping linking elements
1150
a
,
1150
b
are attached to arms
1151
a
and
1151
b
, respectively, at one end and to the respective flap bars
1128
a
,
1128
b
at the other end, respectively. Arms
1151
a
,
1151
b
are attached to partially toothed gears
1152
a
,
1152
b
, respectively. A central gear
1160
is positioned between the gears
1152
a
and
1152
b
to engage them, and is operated, through a linking element
1165
and a steering vane
1170
, by the helm
1114
.
FIG. 18
illustrates the operation of the flaps when the watercraft is turning to the right, or starboard, direction.
Because the gears
1152
a
,
1152
b
are only partially toothed, when attempting a starboard turn, only the right gear
1152
b
will be engaged by the central gear
1160
. Therefore, the left flap
1116
a
does not move but, rather, stays in a parallel position to the outer surface of the hull of the PWC
1100
. Thus, in this configuration, the right flap
1116
b
is the only flap in an operating position to assist in the steering of the watercraft
1100
.
While the steering system of
FIG. 18
provides some level of improved steering control, the system suffers from certain deficiencies. First, steering is physically difficult. When the flap bars
1128
are located at the front portion of the flaps
1116
(as shown), the user must expend considerable effort to force the flaps
1116
a
,
1116
b
out into the flow of water. Second, the force needed to force the flaps
1116
a
,
1116
b
into the water stream causes considerable stress to be applied to the internal steering cabling system that may cause the cabling system to weaken to the point of failure. Third, only one flap
1116
b
is used at any given moment to assist in low speed steering. Therefore, steering assistance is provided on one side of the watercraft only. Fourth, when the helm is turned, the one usable flap is always operative. Thus, when the helm is turned while the watercraft is operating at a high speed, with sufficient thrust, the flap is pivoted into the high pressure flow of water past the hull. This can cause damage to the flap and its associated components and can make handling more aggressive.
Thus, the steering system shown in
FIG. 18
is difficult to use, applies unacceptable stresses to the internal steering system, relies on only half of the steering flaps to effectuate a turn, and cannot be disengaged when steering assistance is not desired.
For at least these reasons, a need has developed for an off-power steering system that is more effective in steering a jet powered watercraft, especially a PWC, when the thrust is inadequate because the pump pressure has fallen below a predetermined threshold. Preferably, the steering system should provide accurate handling with easy operation.
SUMMARY OF THE INVENTION
Therefore, one aspect of embodiments of this invention provides an off-power steering system that does not cause undue stress on the driver or the helm control steering mechanisms.
An additional aspect of the present invention provides an off-power steering mechanism that does not interfere with operation of the watercraft when sufficient thrust is generated by the jet pump to steer the watercraft.
A further aspect of the present inven
Adamczyk Rick
Berthlaume Yves
Plante Rénald
Simard Richard
Bombardier Inc.
Pillsbury & Winthrop LLP
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