Tilt and trim arrangement for marine propulsion

Details Tilt and trim arrangement for marine propulsion Tilt and trim arrangement for marine propulsion

1999-10-27

2001-09-11

Morano, S. Joseph (Department: 3617)

Marine propulsion

Screw propeller

With means effecting or facilitating movement of propulsion...

Reexamination Certificate

active

06287160

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a tilt and trim arrangement for a marine propulsion, and more particularly to an improved tilt and trim arrangement that is reinforced against external force while remaining compact.
2. Description of Related Art
Marine outboard drives, i.e., both outboard motors and the outboard drive sections of inboard motors, have drive units mounted on an associated watercraft by a tilt and trim arrangement or bracket assembly which comprises a swivel bracket and a clamping bracket. The swivel bracket carries the outboard drive unit for pivotal movement about a generally vertically extending steering axis. The clamping bracket, in turn, is affixed to the associated watercraft and supports the swivel bracket for pivotal movement about a generally horizontally extending tilt axis.
The bracket assembly includes a hydraulic tilt device disposed between the swivel bracket and the clamping bracket so that the swivel bracket is tilted up or down relative to the clamping bracket. The hydraulic tilt device is, for example, a compound tilt and trim cylinder assembly.
The hydraulic tilt device includes a cylinder assembly having a cylinder housing which defines a cavity therein. A piston is slidably supported in the cavity. A piston rod is affixed to the piston and extends beyond the cavity. The swivel bracket has a pair of ribs spaced apart transversely from each other and a pivot pin extends between them. The piston rod is affixed on the pivot pin for pivotal movement. Meanwhile, the clamping bracket also has a pair of ribs spaced apart transversely from each other and another pivot pin extends between them. The cylinder housing is affixed on this pivot pin for pivotal movement. A powering assembly is provided for pressurizing working fluid in the cavity of the cylinder housing. The powering assembly includes an electric motor, a hydraulic pump and a reservoir, all of which are relatively bulky. With the reciprocal movement of the piston in the cavity of the cylinder housing, the piston rod extends from or contracts into the housing and the drive unit, thereby, is tilted up or down in a certain range.
Recently, outboard motors are inclined to have larger engines than before because more powerful and high speed propulsions are desired. This trend necessarily invites large sized drive units to support such large engines which are quite heavy as well as unwieldy. In addition, these outboard motors produce large thrust force. The bracket assembly accordingly must support a heavy drive unit and receive such a large thrust force. The ribs and hydraulic tilt assembly need to be bigger and have more sufficient rigidity in order to withstand the increased weight of the drive and the increased spacing necessary to receive the larger powering assembly. In fact, the bulky cylinder housing and powering assembly are likely to cause a problem as to how they are disposed in a limited space between the rigid ribs.
Some conventional bracket assemblies have a cylinder assembly and a powering assembly positioned side-by-side to each other. However, a cylinder housing of this cylinder assembly must be off-centered and hence produces a torque upon the ribs when the cylinder extends and contracts. Thus, the ribs require reinforcement and, if reinforced, they are larger, which further exacerbates the arrangement of the cylinder and powering assembly between the clamping and swivel brackets.
Other conventional bracket assemblies have a cylinder housing spaced widely from the swivel bracket. This arrangement, however, does not present a compact bracket assembly.
SUMMARY OF THE INVENTION
A need therefore exists for a compact tilt and trim arrangement for a marine propulsion with sufficiently reinforced ribs to support larger outboard motors.
In accordance with one aspect of the present invention, a tilt and trim arrangement for a marine outboard drive comprises a swivel bracket carrying a drive unit for pivotal movement about a generally vertically extending axis. The swivel bracket is provided and includes a pair of ribs spaced apart transversely from each other. A clamping bracket is adapted to be affixed to an associated watercraft and supports the swivel bracket for pivotal movement about a generally horizontally extending axis. A hydraulic tilt device is provided and includes a cylinder housing defining a cavity therein. A piston assembly is slidably supported in the cavity. A piston rod is affixed to the piston assembly and extends beyond the cavity. The cylinder housing includes a tilt section and a trim section. An outer diameter of the tilt section is smaller than an outer diameter of the trim section. The piston rod extends within the tilt section. A first pivotal connection couples the piston rod to the swivel bracket at a position generally between the ribs. Second pivotal connection couples the cylinder housing to the clamping bracket. The tilt section is generally positioned between the ribs of the swivel bracket at least when the piston rod exists almost fully within the cylinder housing.
In accordance with another aspect of the present invention, a tilt and trim arrangement for a marine outboard drive comprises a swivel bracket carrying a drive unit for pivotal movement about a generally vertically extending axis. A clamping bracket is adapted to be affixed to an associated watercraft and supports the swivel bracket for pivotal movement about a generally horizontally extending axis. A tilt and trim device is provided and includes a housing having a tilt section and a trim section. An outer diameter of the tilt section is smaller than an outer diameter of the trim section. The tilt section defines a tilt cavity and has a tilt piston slidably movable within the tilt cavity. The trim section defines a trim cavity and has a trim piston slidably movable only within the trim cavity. An inner diameter of the tilt cavity is smaller than an inner diameter of the trim cavity. A piston rod is affixed to the tilt piston and extends beyond the tilt cavity. A first pivotal connection couples the piston rod to the swivel bracket, and a second pivotal connection couples the cylinder to the clamping bracket. Both the trim piston and the tilt piston move as a unit to move the drive unit in a trim range and only the tilt piston moves to move the drive unit in a tilt range. The swivel bracket has a pair of ribs spaced apart transversely relative to each other. The tilt section is generally positioned between the ribs at least when the piston rod exists almost fully within the cylinder.
In accordance with a further aspect of the present invention, a tilt and trim arrangement for a marine outboard drive comprises a swivel bracket carrying a drive unit for pivotal movement about a vertically extending steering axis. The swivel bracket is provided and includes a pair of ribs spaced apart transversely from each other. A clamping bracket is adapted to be affixed to an associated watercraft and supports the swivel bracket for pivotal movement about a horizontally extending tilt axis. A tilt and trim device is placed between the swivel bracket and the clamping bracket for tilting the swivel bracket. The tilt and trim device includes a cylinder housing which defines a cavity therein. A piston is slidably supported in the cavity and a piston rod is affixed to the piston. The cylinder housing has a lower section and an upper section which diameter is smaller than the lower section. The piston rod extends outwardly from the upper section and is affixed to the ribs for pivotal movement. The upper section is generally positioned between the respective ribs at least when the piston rod is fully retracted within the cylinder housing.
Further aspects, features and advantages of this invention will become apparent from the detailed description of the preferred embodiment which follows.


REFERENCES:
patent: 2953335 (1960-09-01), Kiekhaefer
patent: 4501562 (1985-02-01), Blanchard
patent: 4557696 (1985-12-01), Nakahama
patent: 5149286 (1992-09-01), Tsujii
patent: 5156

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