Marine propulsion – Screw propeller – With means effecting or facilitating movement of propulsion...
Reexamination Certificate
1998-08-18
2001-06-19
Swinehart, Ed (Department: 3617)
Marine propulsion
Screw propeller
With means effecting or facilitating movement of propulsion...
C440S083000, C440S053000
Reexamination Certificate
active
06247979
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a direct boat drive, and in particular to an inboard/outboard boat drive which couples an inboard engine to a propeller enabling steering and trim adjustment.
BACKGROUND OF THE INVENTION
Many boats are driven by internal combustion engines, which may be of the inboard or outboard type. Outboard engines are typically pivotally mounted on the stern of the boat allowing for steering without the need for a separate rudder, and enabling adjustment of the angle between the propeller drive and the hull for changes in boat trim. The pivotal mounting also allows boats fitted with such outboard engines to run up on to beaches with the propeller pivoted above the lower surface of the hull, preventing damage thereof.
Inboard engines are typically attached through a transmission or gearbox directly to the propeller shaft, and are necessarily mounted toward the center of the boat with a long propeller shaft to allow the propeller to minimize the drive angle between the propeller shaft and hull waterline. Such installations are necessarily bulky, and installation of the engine toward the center of the hull provides undesirable weight distribution characteristics in planing type hulls, which ideally have the heavy engine installed toward the rear of the boat.
To provide inboard engine installations with the advantages of outboard engine installations detailed above, inboard/outboard installations have been developed. These installations couple an inboard engine mounted within the hull of the boat to a drive assembly and propeller arrangement similar to that of an outboard engine installation, the engine essentially being connected through a ‘leg’ to the propeller. The engine can thus be mounted toward the rear of the boat, and steering and trim control provided in a compact installation.
The mechanical system through which the power is transmitted usually consists of a drive-train of complex gearing, together with a number of joint systems so as to achieve steering and a measure of trim control. Such systems are mechanically complex and intrinsically inefficient. The power which may be transmitted through such devices is limited by the physical size of the devices, requiring the use of multiple engines and drives for high performance boats.
OBJECT OF THE INVENTION
It is the object of the present invention to overcome or substantially ameliorate at least some of the above disadvantages.
SUMMARY OF THE INVENTION
There is disclosed herein an inboard-outboard boat drive comprising:
a housing having a first end, a second end and a cavity passing between said housing first and second ends;
pivotal mounting means for pivotally mounting said housing first end on a stern section of a boat, enabling pivotal movement about a pivot point;
an input drive shaft having first and second ends, said first end being adapted to be coupled to an engine mounted in said boat;
an intermediate drive shaft disposed within said cavity and having a first end towards said housing first end and a second end towards said housing second end;
a first universal joint coupling said input drive shaft second end to said intermediate drive shaft first end, said first universal joint being disposed about said pivot point to enable pivotal movement of said intermediate drive shaft about said pivot point;
an output drive shaft having first and second ends, said output drive shaft second end being adapted to be coupled to a propulsion element; and
a second universal joint coupling said intermediate shaft second end to said output shaft first end.
Generally, each of said first and second universal joints is a constant velocity universal joint.
Typically said pivotal mounting means comprises a semi-spherical joint in the general form of a ball and socket arrangement.
Typically said semi-spherical joint includes:
a semi-spherical female socket member provided at said housing first end and adapted to be fastened to said stern section, and
a semi-spherical male ball type member disposed within said semi-spherical socket member. In such an arrangement the cavity passes through said semi-spherical male ball type member such that said first universal joint is generally concentrically positioned within said semi-spherical male ball type member and about said pivot point.
Preferably separate steering and trim control elements are mounted on said housing for steering and trim control.
Preferably said trim control element is a hydraulic ram.
Alternatively a control lever is mounted on said semi-spherical ball-type member for steering and/or trim control.
Preferably said input shaft is mounted in bearings disposed within a bearing housing fastened to, or integral with, said semi-spherical female socket member.
Preferably said output shaft is mounted in bearings disposed within said cavity towards said housing second end.
Preferably a seal is provided in said cavity at said housing second end.
REFERENCES:
patent: 4645463 (1987-02-01), Arneson
patent: 4976638 (1990-12-01), Grinde
patent: 5167548 (1992-12-01), Thiger
patent: 5421754 (1995-06-01), Lund-Anderson
patent: 0407630 (1991-01-01), None
DBD Marine Pty. Ltd.
Ladas & Parry
Swinehart Ed
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