Marine propulsion – Engine – motor – or transmission control means
Reexamination Certificate
1999-09-27
2001-10-16
Basinger, Sherman (Department: 3617)
Marine propulsion
Engine, motor, or transmission control means
C440S08800J, C123S090170
Reexamination Certificate
active
06302751
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to driving engines for watercraft, and, more particularly, engines for small watercraft that plane across the surface of the water.
2. Description of Related Art
Small planing watercraft, sometimes referred to as “personal watercraft,” are typically configured with a bench seat that the driver and any passengers straddle while the driver grasps handlebars that are used to steer the watercraft. The engine is typically mounted in an engine compartment formed in a hull structure below a deck portion so that the output from the engine is transmitted directly, without a transmission, to a propulsion unit. At low engine RPM, and corresponding low velocity, the hull of the watercraft parts the water in what is referred to as a “non-planning” condition. As the engine speed and velocity of the watercraft increase, the watercraft bow rises until the watercraft crosses the so-called “hump” where the watercraft transitions from non-planing motion, where the hull splits the water, to planing motion where the hull skims over the surface of the water. Such small planing watercraft are typically equipped with high-speed, high-output engines which expel exhaust gases into the water at the stern of the watercraft and generally provide good mobility during planing motion. However, conventional high speed, high output watercraft engines have been found to produce insufficient power at lower engine speeds (RPM's) to enable the craft to move smoothly and quickly “over the hump” through the transition from non-planing to planing movement.
BRIEF SUMMARY OF THE INVENTION
The present invention addresses these and other drawbacks of conventional technology by providing a small planing watercraft with a high-RPM, high-output engine which can make a smooth transition from non-planing to planing movement. The watercraft includes a hull or shell, a propulsion unit arranged in the hull, and an engine arranged in an engine compartment in the hull for directly driving the propulsion unit. The engine includes an exhaust passage, at least one air intake valve, an air intake valve camshaft for opening and closing the air intake valve, and valve timing control means for advancing the normal closure of the air intake valve when the watercraft and engine are operating below a predetermined speed or RPM at which the watercraft transitions from non-planing motion to planing motion. The predetermined speed of the watercraft is directly related to a predetermined engine RPM.
The valve timing control means may include a toothed intake camshaft drive pulley mounted on the end of the intake valve camshaft and operatively connected (e.g., by a toothed belt) with the crankshaft for rotation therewith, and means for selectively rotating the pulley relative to the intake camshaft for advancing the closure of the air intake valve when the engine is operating below the predetermined speed. More particularly, the selective rotating means may include an inner shaft fixed on the end of the intake valve camshaft and having helical splines arranged on its outer surface. An annular sliding piston is slidably arranged around the inner shaft with helical splines on its inner surface for engaging the splines on outer surface of the inner shaft. The piston also has oppositely twisted helical splines on its outer surface for engaging similar splines inside an interior cylindrical opening of the pulley. All of the splines are arranged so as to rotate the pulley relative to the camshaft in response to axial translation of the annular piston.
The engine may also include a long air intake passage for low RPM operation and a short air intake passage for high-RPM operation, with an air intake control valve provided in the short air intake passage that includes means for closing the air intake control valve when the watercraft is operating below a predetermined speed. The engine may include an exhaust passage having an exhaust control valve for selectively constricting the exhaust passage by partially closing the exhaust control valve when the watercraft is operating below the predetermined speed.
REFERENCES:
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patent: 4986780 (1991-01-01), Sougawa
patent: 5778857 (1998-07-01), Nakamura et al.
patent: 5782214 (1998-07-01), Nanami et al.
patent: 5816205 (1998-10-01), Moriya
patent: 6015320 (2000-01-01), Nanami
patent: 6027384 (2000-02-01), Nitta et al.
patent: 6041647 (2000-03-01), Matsuoka
patent: 6068530 (2000-05-01), Ozawa
patent: 6076492 (2000-06-01), Takahashi
Bacon & Thomas PLLC
Basinger Sherman
Wright Andrew
Yamaha Hatsudoki Kabushiki Kaisha
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