Patent Application
20070163480
Not Applicable
Not Applicable
This invention relates to the field of through-hull connectors for boats, and more particularly to a cast stainless steel through-hull connector with square threads.
Through-hull connectors are commonly used on boats to direct wastewater and effluent overboard, and as inlets and outlets for engine cooling water. Commonly used materials for through-hull connectors have been bronze, various plastics, and stainless steel. The through-hull connectors typically have a flange disposed against the outside of the hull, a threaded body passing through the hull, and a flange nut tightened against the inside of the hull. A gasket or bedding compound is employed to waterproof the connection. The flange nut can be made of plastic or metal, but plastic is far less expensive, and does not corrode or gall. The threads on the body can be any shape, such as V form, buttress, acme, or square threads. V threads tend to develop tangential or hoop stresses in the nut as it is tightened, due to a radially outward vector component of the axial force on the sloping thread. In the case of a plastic nut with V threads, one mode of failure is breaking under tensile stress. Another mode of failure is the nut expanding under the hoop stress, and the female threads slipping over the male threads. One way to preclude these failure modes is to form the threads in a quadrilateral, preferably a square section, thereby avoiding any radial vector component. Axial forces only will then result from tightening the nut. External quadrilateral threads, such as square and acme threads, are known to be stronger than V threads. Furthermore, V threads are prone to damage at the thread apex or crown, where the section becomes thin.
Square threads can be machined, but heretofore have been difficult to cast. This is because the mold must be opened perpendicular to the axis of the part, and the opposite helix angle on opposite sides of the thread tends to lock the mold halves together. Splitting the mold in four directions is necessary in this case.
Stainless steel is expensive, and some means of minimizing the amount of material in the product would be advantageous. A means of retaining the sealant or bedding compound between the flange and the hull would also be desirable.
Through-hull connectors are known, and have taken a variety of configurations in the past. Some examples of connectors in the prior art are to be found in the following patents:
Green, U.S. Pat. No. 6,736,081; Green, U.S. Pat. No. 6,477,971; Shields, U.S. Pat. No. 6,050,867; Smith, U.S. Pat. No. 6,038,992; Gross, U.S. Pat. No. 5,722,339; Sharpe, U.S. Pat. No. 5,456,499; Meisenburg, U.S. Pat. No. 4,875,884; and DePersia, U.S. Pat. No. 3,565,031; all show a circular fitting with a bore completely through it. The inner end is adapted to accept a hose or tube by means of hose barbs or threads. A flange on one end fits against the hull outer or inner surface, in some cases with a gasket. A nut on the opposite end tightens the fitting on V-threads. None of these connectors discloses a square thread. None shows any way of minimizing the material required. None displays any structure for retaining sealant against the flange.
Accordingly, there is a need to provide a through-hull connector for boats that is made of stainless steel for strength, long service life, and corrosion resistance.
There is a further need to provide a through-hull connector of the type described and that employs quadrilateral threads for strength, and to preclude hoop stresses and consequent failure of the nut.
There is a still further need to provide a through-hull connector of the type described and that will minimize the material required for fabrication.
There is a yet further need to provide a through-hull connector of the type described and that will retain sealant between the flange and the hull.
There is another need to provide a through-hull connector of the type described and that can be manufactured cost-effectively by casting, in large quantities of high quality.
In accordance with the present invention, there is provided a through-hull connector for use in connection with a hull of a boat. The through-hull connector comprises a body extending between opposite first and second ends, and having a central axis. The body has an outside surface and a bore through it. At least one hose barb is provided for attaching a conduit to the second end.
External threads with a generally quadrilateral, and preferably square, cross-section are provided for fastening the through-hull connector to the boat hull. The external threads on the body have a gap extending longitudinally along the outside surface of the body, so as to lighten the connector and save material. A flange nut engages the external threads.
A flange extends outward from the body first end for seating against the hull outer surface. The flange has an annular groove to retain sealant.
The body has a notch extending transversely through the body adjacent the second end. The notch is adapted to engage an elongated tool, such as a screwdriver or a drift pin, to hold the body from rotating as the nut is turned during installation.
A more complete understanding of the present invention may be obtained from consideration of the following description in conjunction with the drawing, in which:
a is a close-up view of a thread of the through-hull connector of
b is a close-up view of yet another embodiment of the thread of the through-hull connector of
c is a close-up view of still another embodiment of the thread of the through-hull connector of
d is a close-up view of a further embodiment of the thread of the through-hull connector of
Referring now to the drawing, and especially to
The external threads 32 on the body 22 have a discontinuity, or gap 34, extending longitudinally along the outside surface 28 of the body 22. Preferably, there are two such gaps 34, spaced apart on opposite sides of the body 22. The gaps 34 save material and lighten the connector, resulting in a further cost saving. Another advantage of the gaps 34 is that when the connector 20 is fabricated as a casting, a mold 29 comprising only two halves is needed, as shown in
The body 22 has a notch 38 extending transversely through the body 22 adjacent the second end 26, the notch 38 being adapted to engage an elongated tool, such as a screwdriver or a drift pin (not shown), so as to preclude rotation of the body 22 during installation.
A flange 40 extends outward from the body first end 24 for seating against the hull outer surface. The flange 40 has a first surface 42 facing the first end 24 and a second surface 44 facing the second end 26. The flange second surface 44 is adapted for seating against the hull outer surface. The flange 40 has an annular groove 46 on the second surface 44 to retain sealant.
Attaching means, specifically one or more hose barbs 48, is provided for attaching a conduit (not shown) to the second end 26. Other attaching means, such as threads, may be used.
The through-hull connector 20 is preferably a casting, and is cast from a material selected from the group consisting of stainless steel, bronze, monel, thermoplastic resin, and thermoset resin. The preferred material is 316L stainless steel.
Turning now to
A flange 140 extends outward from the body first end 124 for seating against the hull outer surface. The flange 140 has a first surface 142 facing the first end 124 and a second surface 144 facing the second end 126. The flange second surface 144 is adapted for seating against the hull outer surface.
Attaching means, specifically one or more hose barbs 148, is provided adjacent the second end 26.
Connector 120 differs from connector 20 in that the external threads 132 on the body 122 are continuous and extend longitudinally along. the outside surface 128 of the body 122. There is no gap in the threads 132. The flange 140 has no annular groove to retain sealant. The body 122 has a key 138 projecting from the bore 130. The key 138 is adapted to engage a circular tool with a keyway (not shown) so as to preclude rotation of the body 122 during installation.
Referring now to
The body 222 has a notch 238 extending transversely through the body 222 adjacent the second end 226, the notch 238 being adapted to engage an elongated tool, so as to preclude rotation of the body 222 during installation.
Attaching means, specifically one or more hose barbs 248, is provided adjacent the second end 226.
Connector 220 differs from connector 20 in that a flange 240 extends outward from the body 222 intermediate the first 224 and second 226 ends. The flange 240 has a first surface 242 facing the first end 224 and a second surface 244 facing the second end 226. The flange first surface 242 is adapted for seating against the hull inner surface. The flange 240 further comprises an annular groove 246 on the first surface 242 of the flange so as to retain sealant.
Numerous modifications and alternative embodiments of the invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. Details of the structure may be varied substantially without departing from the spirit of the invention and the exclusive use of all modifications that will come within the scope of the appended claims is reserved.
Part
No. Description
