Marine propulsion – Screw propeller – With means effecting or facilitating movement of propulsion...
Reexamination Certificate
2001-11-12
2002-10-22
Sotelo, Jesus D. (Department: 3617)
Marine propulsion
Screw propeller
With means effecting or facilitating movement of propulsion...
C440S053000
Reexamination Certificate
active
06468120
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The invention is directed generally to marine engine drive systems designed to supply rotary power down from an engine carried on a boat to a submerged propeller and for imparting the propelling force generated by the rotating propeller in the water back to the boat thereby causing the boat to travel across the water. More particularly, the invention relates to a single hydraulic trim cylinder configuration for pivoting the drive system across a range of possible trim and tilt positions.
2. Background
Traditionally, powerboats have been powered with either an inboard engine, an outboard engine, or an inboard/outboard engine. In the inboard configuration, the engine is typically positioned within an engine compartment or engine room that is carried on the boat. A drive shaft of the assembly extends through a bottom surface of the hull of the boat with a propeller positioned thereupon, but exteriorly to the boat. The drive shaft and propeller remain in the water during normal operation of the boat and typically cannot be removed from the water unless the boat is also taken out of the water. Often, an inboard engine is completely concealed within the engine compartment or engine room below the deck of the boat.
An outboard engine is a self contained unit that is most often attached to the transom of a boat. A typical outboard engine configuration includes an engine that is completely concealed within a cowling, at least one propeller attached to a lower unit, and a drive shaft contained within a drive shaft housing that extends in a generally vertical direction between the engine and the lower unit. The lower unit is typically constructed as a one piece body that is made of aluminum. Further, the lower unit contains gears for transferring torque produced by the engine, and imparted on the drive shaft, to a propeller shaft that is generally oriented perpendicularly to the drive shaft. The lower unit includes a skeg for steering purposes, an anti-cavitation plate, and a cylindrical bore that houses a forward gear, a reverse gear, and a propeller shaft. The lower unit usually also includes water intake ports for receiving raw water that is used to cool the engine. Further, the lower unit is coupled to a drive shaft housing, or upper housing, using a set of five to ten bolts.
Most outboard engines manufactured today further include a tilt/trim system that enables the outboard engine to be tilted through various angles to improve the performance of a boat and to rotate the lower end of the power plant out of the water. Generally, outboard engines can be trimmed between angles relative to a vertical axis of about minus 5 degrees to about plus 15 degrees and can be tilted through a range of angles between 15 degrees and about 60 degrees. The trim/tilt system generally is composed of three hydraulic cylinders, one cylinder that is the tilt mechanism and two cylinders that combine with the tilt cylinder to form a trim mechanism. The trim range includes a range of angles within which an engine can be operated to power the carrying boat while a tilt range includes a range of angles within which the engine generally will not be operated to power the boat; that is, the tilt range is for use when the engine is not running. The trim function moves the engine through the described range of angles about half as fast as the tilt function moves the engine because trim adjustment is used to adjust the drive leg through the trim range of angles when the boat is traveling, often at relatively high rates of speeds. Further, the trim feature operates at this reduced speed for safety concerns since relatively small trim adjustments can significantly affect the attitude of the boat. It also permits an operator to fine tune the travel position of the boat as it travels across the water for enhanced performance.
The tilt mechanism typically enables an entire outboard engine, or substantially all of the engine, to be tilted out of the water while the boat remains in the water. This feature is advantageous for many reasons. It is used during the boat launch and the retrieval process to protect the drive unit, and particularly the lower end from damaging strikes. Even if the boat is not removed from the water, the positioning of the drive leg outside the water using the tilt function prevents aquatic growth, such as algae, barnacles, and other marine plants and animals, from developing on the lower unit. Water, and especially salt water, can be highly corrosive. Salt water corrodes metals and provides a prime environment for galvanic reactions that accelerate decay of metals. Thus, removing the drive assembly from the water when not in use can increase its life dramatically.
The inboard/outboard engine configuration is a hybrid between the inboard and the outboard engine configuration just as the name implies. The inboard/outboard engine configuration generally includes a motor that is positioned within an engine compartment, much like the inboard engine configuration. Unlike the inboard engine which may be located mid-ship, however, the inboard/outboard engine compartment is typically located proximate the transom of the boat. The inboard/outboard engine further includes a drive assembly resembling the lower unit of an outboard engine. The drive assembly of an inboard/outboard power plant, however, is not coupled to a drive housing as described above relative to outboard engines. Instead, the drive assembly includes a shield assembly that is coupled to the transom of a boat.
The drive assembly of the inboard/outboard engine further includes a tilt/trim assembly that has a function similar to the tilt/trim assemblies found on outboard engines and described above. The conventional tilt/trim assemblies for inboard/outboard engines, however, are usually designed differently than those for outboard engines. Specifically, the conventional inboard/outboard tilt/trim assemblies include two hydraulic cylinders. One hydraulic cylinder is attached to one side of the drive assembly proximate the cavitation plate and the other hydraulic cylinder is attached to the other side of the assembly near the cavitation plate. Each cylinder is oriented generally parallel to the cavitation plate. With the hydraulic trim cylinders attached in this fashion, the cylinders produce unwanted water spray during operation of the engine while the boat is traveling on plane. Specifically, as the boat is planing, water travels on top of the cavitation plate and contacts the hydraulic cylinders near where they are attached to the drive assembly. The water is deflected and forms a spray that is unattractive and can cause the back portion of a boat to become wet, including any nearby passengers.
Though there are some drawbacks to traditional inboard/outboard designs, the design still possesses attributes that make it highly desired by many boaters. For instance, inboard/outboard engines can include a closed-loop water cooling system that uses recirculated cooling fluid. This closed-loop system eliminates corrosion problems associated with using raw salt water as encountered in outboard engine. Because a closed-loop cooling system weighs significantly more than a raw water cooling system, typical outboard motors do not have closed-loop water cooling systems. Further, the inboard/outboard engine is usually quieter than most outboard engines and thus desired by some boaters. Additionally, the low profile of inboard/outboard power plants do not provide an obstacle at the transom of the boat, such as the obstacle produced by the elevated engine portion of an outboard power plant. Instead, a relatively unobstructed transom is presented by the low-rise inboard/outboard power plant. As a result, inboard/outboard engines allow boats to include unobstructed swim platforms that extend across the entire transom of a boat which is something that is not normally possible when using an outboard engine. Thus, these and other attributes not mentioned make an inboard/outboard engine the desired engine for many boa
Hasl Emil
Holmberg Rickard
Savineau Cedric
Savoie Chris
Wilkins Matt
AB Volvo Penta
Howrey Simon Arnold & White , LLP
Sotelo Jesus D.
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