Inductor devices – With outer casing or housing
Reexamination Certificate
2001-02-20
2001-10-30
Mai, Anh (Department: 2832)
Inductor devices
With outer casing or housing
C336S096000, C336S205000
Reexamination Certificate
active
06310533
ABSTRACT:
TECHNICAL FIELD
Water-resistant encapsulation of solenoids allowing underwater operation.
BACKGROUND
Manufacturers have encapsulated solenoid coils in plastic to make the coils resistant to water penetration. This process has protected solenoids against minimal pressure water spray, but it has been unable to protect solenoids to withstand submersion to pressure depth.
Solenoid failure is common and troublesome in high-moisture and underwater environments. Unfortunately, numerous applications expose solenoids to moisture and submersion. As a result, there is a great need for solenoids that can reliably resist water penetration and can operate effectively when submerged.
This invention defines a new way to encapsulate solenoids, making them resistant to water, even at significant depths and pressures. This improvement aims at a low cost solenoid that operates reliably underwater.
SUMMARY OF THE INVENTION
This invention introduces a new way to make solenoids water resistant by using compatible and bondable resins to effectuate bonds that are capable of resisting penetration by water. Several bonds must meet this requirement. The encapsulating resin must bond to the resin flanges of a bobbin holding the winding, and the encapsulating resin must bond to the resin insulation of the lead-in wires connected to the solenoid. Forming the bobbin, the lead-in wire insulation, and the encapsulation all of the same or a similar resin ensures compatibility and leads to secure bonds, providing a suitable resin is selected.
A resin suitable for the required bonds is not necessarily optimum for a solenoid bobbin, so it is preferred that the bobbin have a reinforcing core. The bobbin flanges preferably have extra surface area to facilitate rapid heat transfer and bonding during encapsulation. Also, since a housing is often used with a solenoid, the encapsulation is preferably accomplished within a housing. Before using the housing in this way its interior should, preferably, be coated with polytetrafluoroethylene or a similar material to prevent the encapsulating resin from bonding to the housing. Otherwise, the encapsulating resin could crack due to the expansion and contraction of the metal housing during normal in-use temperature cycling.
The resulting encapsulated solenoid is capable of resisting water penetration to significant depths and pressures and operates reliably in a variety of environments.
REFERENCES:
patent: 4233583 (1980-11-01), Novacek
patent: 5138292 (1992-08-01), Forster
patent: 5181004 (1993-01-01), Johnson
patent: 5204044 (1993-04-01), Yoneshige
patent: 5424704 (1995-06-01), Dolle
patent: 5665429 (1997-09-01), Elkwakil
patent: 5710535 (1998-01-01), Goloff
patent: 6076550 (2000-06-01), Hiraishi et al.
Cliftronics, Inc.
Eugene Stephens & Associates
Mai Anh
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