Marine propulsion – Screw propeller – With means effecting or facilitating movement of propulsion...
Patent
1993-10-19
1995-03-21
Swinehart, Edwin L.
Marine propulsion
Screw propeller
With means effecting or facilitating movement of propulsion...
114144R, 440 61, B63H 512
Patent
active
053991125
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a servo-assisted steering arrangement comprising an operating cable connected to a steering wheel mechanism and displaceable in a casing, said operating cable having one end connected to an operating rod dispaceable in a rigid tube and connectable to a steering mechanism, and an hydraulic piston-cylinder device connected to a hydraulic pump via a servo valve and designed to be coupled to the steering mechanism, said servo valve having an operating element which can be acted on by the operating cable to activate the piston cylinder device and which comprises a tubular element limitedly displaceably relative to the servo valve housing
BACKGROUND OF THE INVENTION
In a known boat steering device of this type, the piston cylinder device, the servo valve and the tubular element which is limitedly displaceable form an integrated servo unit. The tubular element serving as an operating element for the servo valve forms in this case the rigid tube to which the operating cable casing is connected and which forms a guide for the operating rod.
Such a servo-assisted steering arrangement requires greater space athwartships (transversely to the boat) than a non-servo-assisted cable steering arrangement, due to the fact that the mounting of the cable casing in the guide tube of the operating rod is displaced when the cable with its operating rod is moved from its ordinary guide tube to the tubular element which is integrated with the servo valve of the servo-unit. This can create problems in boats in which the engine insulation is such that the space athwartships between for example a steering arm of a rudder or a steerable outboard drive-unit and the boat hull is limited. The reason that problems arise when the distance between the steering arm and the hull is small is that the radius of curvature of the operating cable will be small. This results, on the one hand, in increased friction between the cable and the casing and on the other hand to tensions which affects the control of the servo valve. Especially in boats with double engines with outboard drive units, in which the cable steering arrangement is connected to the steering arm of one of the drive units and is connected to the steering arm to the other drive unit via a tie rod, the space available can make it impossible to use a servo-unit of the type described.
OBJECTION OF THE INVENTION
The purpose of the present invention is to achieve a steering device of the type described by way of introduction which requires less space athwartships than the known device described above.
SUMMARY OF THE INVENTION
This is achieved according to the invention by virtue of the fact that the rigid tube is joined to the tubular element in a position parallell to the latter.
The invention is quite simply based on the idea of keeping the cable casing fixed to the ordinary guide tube and mounting said ordinary guide tube to the outside of the tubular operating element of the servo valve instead of moving said components from the guide tube to the tubular operating element of the servo valve. This means that the mounting of the cable casing can be closer to the centre of the engine, which in turn permits a greater radius of curvature for the operating cable.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described in more detail with reference to the accompanying drawings, where FIG. 1 shows a sideview of a previously known servo-assisted steering device for boats and FIG. 2 shows a sideview of a preferred embodiment of steering device according to the invention.
DETAILED DESCRIPTION OF THE PRIOR ART
In FIG. 1 designates a boat steering wheel which is connected to a transmission device 2, which upon turning the wheel displaces a cable 4 in its casing 3. The device 2 can be of any suitable type known per se as can the casing 3 of the cable 4, which form a common push-pull cable for steering the boat.
The cable casing is screwed securely to the end of a valve tube 5 forming the guide for an operating rod 6 j
REFERENCES:
patent: 4595370 (1986-06-01), Small
patent: 4744777 (1988-05-01), Ferguson
Arvidsson Lennart
Bohlin Stig
AB Volvo Penta
Swinehart Edwin L.
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