Marine propulsion – Screw propeller – Having transmission
Patent
1997-01-23
1998-05-26
Avila, Stephen
Marine propulsion
Screw propeller
Having transmission
440 80, B63H 2014
Patent
active
057556059
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a propeller drive installation in a boat, comprising at least two propeller drive units coupled to a drive plant, said drive units each having a first angle gearing enclosed in an upper gear housing and having first and second shafts, of which one is an input shaft intended to be coupled to a drive plant, and a drive unit leg extending downward from the upper gear housing with a second angle gearing enclosed in a lower gear housing and having at least one propeller shaft.
Marine drive plants can, in principle, be divided into two main groups, firstly, traditional inboard installations, in which the engine and transmission (reversing gear) are placed inboard and are coupled to a relatively long, rigid propeller shaft which extends obliquely downwards and aft and out through a sealed bearing in the bottom of the boat, and, secondly, so-called inboard-outboard drive installations, in which a motor mounted inboards is coupled to a propeller drive unit with a propeller leg, which is completely or partially disposed on the outside of the boat hull and has a lower bevel gear with a short horizontal propeller shaft. In the most common type of inboard-outboard drive, the propeller drive unit is tiltably and pivotally hung on a shell mounted on the outside of the boat transom. This type of drive is often twin mounted in fast motorboats of up to 35 ft in length, and the drives are always mounted with the legs parallel to each other.
In order to quickly get a fast planing boat up into the planing position and in order to trim the running position of the boat to adjust for load distribution and wind conditions, flaps, so-called trim tabs, hinged to the lower portion of the transom, are used. They can be maneuvered from the helm position with the aid of electrical or hydraulic means.
The purpose of the present invention is to achieve a drive installation of the type described by way of introduction which is arranged so that the drives can take over the function of the known trim tabs, so that they can be eliminated.
This is achieved according to the invention by virtue of the fact that the drives are mounted beside each other with their respective legs inclined relative to each other, so that the distance between the lower gear housings is greater than the distance between the upper gear housings, and in that one leg is settable to turn the boat in one direction at the same time as the other leg is settable to turn the boat in the opposite direction, whereby the counteracting horizontal force components cancel each other, while the vertical force components are added to each other to trim the running position of the boat in the water.
In a preferred embodiment of the drive installation according to the invention, the drive unit legs each extend through an individual opening in a V-bottomed boat, each drive unit leg having an upper portion which is mounted in rolling bearings in a bearing housing fixed to the upper gear housing.
The rotatable mounting of the drive unit leg relative to the upper gear housing provides unsurpassed maneuverability in comparison to the completely inboard installation and is better than conventional inboard-outboard drives, which all have a limited steering angle range. A drive unit leg rotatably projecting through an opening in the boat bottom can theoretically be rotated 360.degree. and thus, when rotated 90.degree. from a position for dead ahead propulsion, can function in the same manner as a bow propeller, i.e. exerting purely lateral forces on the boat hull and thus making docking and casting off much easier.
The invention will be described in more detail with reference to examples shown in the accompanying drawings, where FIG. 1 shows a cross section through a propeller drive installation according to the invention with twin propeller units, FIG. 2 is an enlargement of the left-hand drive unit shown in FIG. 1, FIG. 3 is a longitudinal section through a drive unit in FIG. 1, and FIG. 4 is a longitudinal section through a second embodiment of a propeller d
REFERENCES:
patent: 3330239 (1967-07-01), Dornak
patent: 4815996 (1989-03-01), Carr
patent: 5134949 (1992-08-01), Almog et al.
AB Volvo Penta
Avila Stephen
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