Ships – Motorized self-propelled waterski or waterscooter-type vehicle
Reexamination Certificate
1999-11-30
2001-07-03
Swinehart, Ed (Department: 3617)
Ships
Motorized self-propelled waterski or waterscooter-type vehicle
C440S08900C
Reexamination Certificate
active
06253696
ABSTRACT:
PRIORITY INFORMATION
This application is based on and claims priority to Japanese Patent Application No. 10-339861, filed Nov. 30, 1998, the entire, contents of which is hereby expressly incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to an engine for a watercraft, and more particularly to mount for mounting engine components to an engine with separate cylinder bodies.
2. Description of Related Art
Personal watercraft have become popular in recent years. This type of watercraft is sporty in nature; it turns swiftly, is easily maneuverable, and accelerates quickly. Personal watercraft today commonly carry one driver and one or two passengers and include a hull which defines an interior engine compartment for housing an engine. The output shaft of the engine is coupled to a water propulsion device of the watercraft, such as a jet propulsion unit. An internal combustion engine is commonly used to power the personal watercraft. Typically, the engine is an in-line, multi-cylinder, two-cycle engine.
The engine includes a cylinder block that defines one or more cylinder bores. The number of cylinder bores corresponds to the desired number of cylinders. The cylinder bores are often lined with steel by pressing a steel sleeves into each cylinder bore. The cylinder bore and steel sleeve together define a cylinder in which a piston reciprocates.
Instead of using steel sleeves to line the cylinder bore, engine manufacturers have recently begun to plate the cylinder bores with a suitable material such as a Nickel alloy. However, engine manufacturers have found it difficult to simultaneously plate multiple cylinder bores when multiple cylinder bores are formed in a single cylinder block. In contrast, it is much easier to plate a single cylinder bore that is contained within it's own separate body. Engine manufacturers have therefore created engines with separate cylinder bodies for each cylinder bore in order to ease the manufacturing process.
Using separate cylinder bodies in an engine has additional advantages over conventional engine blocks. For example, because cylinder bodies are modular and can be combined to form one, two, three or four cylinder engines, they can be mass produced.
There are, however, disadvantages associated with using separate cylinder bodies. For example, in traditional engines the engine block provided a convenient secure place to mount heavy engine components. In comparison, mounting heavy engine components onto separate cylinder bodies can cause uneven loading of a cylinder body with respect to the other cylinder bodies. This uneven loading can cause a cylinder body to twist with respect to the other cylinder bodies and the crankshaft thereby causing damage to other engine components such as the pistons, the crankshaft, and crankcase.
SUMMARY OF THE INVENTION
An aspect of the present invention involves an engine comprising at least two separate cylinder bodies. The cylinder bodies are disposed adjacent to each other, and each cylinder body defines a cylinder bore. The engine also includes a number of pistons equal to the number of cylinder bodies. Each piston is sliceable supported within one of the cylinder bores. A rotational output shaft is coupled to the pistons such that axial reciprocal movement of the pistons within the cylinder bores rotates the output shaft. An exhaust system communicates with the cylinder bores to discharge exhaust gases from the engine. A stay is supported by and extends between the two adjacent cylinder bodies. The stay is arranged to support a component of the engine. Because the load is shared by the two separate and adjacent cylinder bodies, the weight of the supported engine components is shared by the cylinder bodies to inhibit flexion or twisting of the cylinder bodies about the output shaft axis. That is, the resulting structure between the stay and the cylinder bodies provides rigidity to the engine in the direction of the output shaft axis.
In one mode, the engine is disposed within an engine compartment of a small watercraft. The output shaft of the engine is arranged to drive a propulsion device of the watercraft to propel the watercraft. In a further variation, the stay supports a portion of the exhaust system, and preferably an exhaust chamber that houses a catalyst device. Thus, this heavy component of the exhaust system is supported by two separate cylinder bodies for the above-noted purpose.
Further aspects, features, and advantages of the present invention will become apparent from the detailed description of the preferred embodiment that follows.
REFERENCES:
patent: 4068645 (1978-01-01), Jenkinson
patent: 5168838 (1992-12-01), Seike et al.
patent: 5524596 (1996-06-01), Nakai et al.
patent: 5632660 (1997-05-01), Nakase et al.
Knobbe Martens Olson & Bear LLP
Swinehart Ed
Yamaha Hatsudoki Kabushiki Kaisha
LandOfFree
Marine engine for small watercraft does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Marine engine for small watercraft, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Marine engine for small watercraft will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2553459