Marine propulsion – Screw propeller – With means effecting or facilitating movement of propulsion...
Reexamination Certificate
2000-04-19
2001-12-25
Swinehart, Ed (Department: 3617)
Marine propulsion
Screw propeller
With means effecting or facilitating movement of propulsion...
Reexamination Certificate
active
06332817
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a trim-tilt device for a marine propulsion unit such as an outboard motor or inboard/outboard motor.
2. Description of the Related Art
Conventionally, the trim-tilt device for a marine propulsion unit has a cylinder device interposed between a hull and the propulsion unit which is tiltably supported by the hull. By controlling supply and discharge of hydraulic fluid from a hydraulic fluid supply/discharge device to a cylinder device or vice versa, the cylinder device is expanded and contracted to thereby trim and tilt the marine propulsion unit.
As disclosed in U.S. Pat. No. 3,250,240, there is, as a cylinder device for a conventional trim-tilt device for a marine propulsion unit, a housing connected to one of a hull and a marine propulsion unit and which forms a large-diameter trim chamber; a cylinder that is telescopically inserted into the trim chamber of the housing and which forms a small-diameter tilt chamber; a large-diameter trim piston that is fixed to an end portion of the cylinder within the trim chamber of the housing which partitions the trim chamber into a first trim chamber of a cylinder accommodation side and a second trim chamber of an anti cylinder accommodation side; a piston rod that is connected to the other of the hull and the marine propulsion unit and that is telescopically inserted into the tilt chamber of the cylinder; and a small-diameter tilt piston that is fixed to an end of the piston rod within the tilt chamber of the cylinder and that partitions the tilt chamber into a first tilt chamber of a piston rod accommodation side and a second tilt chamber of an anti piston rod accommodation side. In this prior art, after the cylinder of the cylinder device projects from the housing outward in a trimming operation, the piston rod of the cylinder device projects from the cylinder outward in a tilting operation.
However, the conventional technique has the following problems.
(1) Since the cylinder of the cylinder device serves as a member for transmitting a constant propulsion force (axial compression force) between the hull and the marine propulsion unit, it is required for the cylinder to ensure a fixed strength for accommodating forces at its small area. As a result, the cylinder is structured with metal material such as iron or the like. At this time, in order to make the cylinder rustproof against water or the like, it is necessary to employ high grade rustproof material such as stainless steel or the like as the material for the cylinder, or to perform rustproof processing such as coating or the like on the cylinder, resulting in increased cost.
(2) Since the cylinder of the cylinder device repeatedly slides on a seal member of a cylinder guide provided on the housing in the region of the trimming operation, rust inducing scratching of the seal member must be prevented from occurring on an outer surface of the cylinder. For this reason, in view of this point, in order to make the cylinder rustproof against water or the like, it is also necessary to employ high grade rustproof material such as stainless steel or the like as the material for the cylinder, or to perform rustproof processing such as coating or the like on the cylinder, resulting in increased cost.
(3) When a hydraulic fluid supply/discharge device and the cylinder device are integrated together, a tank constituting the hydraulic fluid supply/discharge device is provided so as to exhibit a significant bulge laterally about a cylinder proximal portion of the cylinder device, and therefore there is a limitation in compact sizing of the tilt device.
The above (2) is a problem specific to the trim-tilt device, but the above (1) and (3) are problems which are not specific to the trim-tilt device but common to various ordinary tilt devices.
SUMMARY OF THE INVENTION
The object of the present invention is to reduce the number of machining steps for a cylinder constituting a tilt device to rustproof the cylinder easily and reliably, and to make the tilt device compact.
According to the present invention, there is disclosed a trim-tilt device for a marine propulsion unit wherein a cylinder device is mounted between a hull and the marine propulsion unit freely tiltably supported by the hull; and wherein a hydraulic fluid is supplied from a hydraulic fluid supply/discharge device into the cylinder device and discharged from the cylinder device into the hydraulic fluid supply/discharge device to thereby expand and contract the cylinder device and thereby trim and tilt the marine propulsion unit. The cylinder device comprises a cylinder connected to one of the hull and the marine propulsion unit and a piston rod connected to the other thereof. The cylinder of the cylinder device is covered with a tank constituting the hydraulic fluid supply/discharge device.
Furthermore, according to the present invention, there is disclosed a trim-tilt device for a marine propulsion unit wherein a cylinder device is mounted between a hull and the marine propulsion unit freely tiltably supported by the hull; and wherein hydraulic fluid is supplied from a hydraulic fluid supply/discharge device into the cylinder device and discharged from the cylinder device into the hydraulic fluid supply/discharge device to thereby expand and contract the cylinder device and thereby trim and tilt the marine propulsion unit. The cylinder device comprises: a housing which is connected to one of the hull and marine propulsion unit and which forms a large-diameter trim chamber; a cylinder which is telescopically inserted into the trim chamber and which forms a small-diameter tilt chamber; a large-diameter trim piston fixed to an end portion of the cylinder within the trim chamber of the housing which partitions the trim chamber into a first trim chamber of a cylinder accommodation side and a second trim chamber of an anti cylinder accommodation side. A piston rod is connected to the other of the hull and the marine propulsion unit, which is telescopically inserted into the tilt chamber of the cylinder; and a small-diameter tilt piston which is fixed to an end portion of the piston rod within the tilt chamber of the cylinder and which partitions the tilt chamber into a first tilt chamber of a piston rod accommodation side and a second tilt chamber of an anti piston rod accommodation side. A portion of the cylinder of the cylinder device which projects from the housing outward in a trimming operation is covered with a tank constituting the hydraulic fluid supply/discharge device.
REFERENCES:
patent: 3250240 (1966-05-01), Ziegler
patent: 5074193 (1991-12-01), Hundertmark
patent: 5149285 (1992-09-01), Kinoshita
patent: 5718613 (1998-02-01), Nakamura
patent: 5975968 (1999-11-01), Nakamura
patent: 0769288 (1995-03-01), None
patent: 0769289 (1995-03-01), None
Orum & Roth
Showa Corporation
Swinehart Ed
LandOfFree
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