Electricity: conductors and insulators – Boxes and housings – Hermetic sealed envelope type
Reexamination Certificate
1999-01-28
2001-06-12
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Boxes and housings
Hermetic sealed envelope type
C361S642000, C361S646000, C361S837000
Reexamination Certificate
active
06245994
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates to a fuse box containing high-power fuse circuitry such that the fuse box enclosure remains intact when the fuse blows. In particular, the present invention relates to a high impact-resistant fuse box.
2. Related Art
Railed vehicles, such as trains, travel along railed tracks and receive electrical power from a third rail that parallels the tracks. The electrical power is ordinarily of the order of a megawatt with currents typically at 1000 amperes and voltages typically at 600 volts. In order to protect the train from an electrical overload, a fuse box is typically mounted on an exterior wall of the locomotive with an input cable electrically coupled to the third rail and an output cable electrically coupled to the engine. The fuse box contains a fuse circuit designed to blow a fuse at a predetermined input current. The fuse is typically 8 inches long and 3 inches in diameter and contains a gas. When the fuse blows, the gas explodes at high temperature and high energy, causing fragments of the fuse material to strike the walls of the fuse box enclosure with great force. Current fuse boxes made of a fiberglass material are not reliably able to withstand the force of such an explosion, resulting in damages that are expensive to repair.
Thus, there is a need for a high impact-resistant fuse box coupled to a railed vehicle, wherein the fuse box is able to remain intact when the fuse blows. Additionally, a need exists for a high impact-resistant fuse box for use with other vehicles and also for static structures.
SUMMARY OF THE INVENTION
Generally, the present invention overcomes the difficulties of the prior art by providing an apparatus structure that comprises a box and an attachment device. The box includes a material having a hardness of at least D-50 on a Shore scale or a material having a hardness of at least A-95 on the Shore scale. The attachment device is within the box and coupled to the box, and is for the purpose of attaching a circuit pattern to the box. The circuit pattern includes a capacity to process an input electric current having a power of at least 0.1 megawatts.
More specifically, the present invention provides an apparatus that comprises a box and an attachment device. The box includes a base and a cover. The base and the cover are each made of an ether-type urethane material having a hardness of at least D-50 on a Shore scale. The cover is coupled to the base. The base includes: at least one first hole through a wall of the base and at least one second hole through the wall of the base. The attachment device is within the box and coupled to the box, and is for the purpose of attaching a circuit pattern to the box. The circuit pattern includes a capacity to process an input electric current having a power of at least 0.1 megawatts, wherein the circuit pattern includes a fuse that blows if the input electric current exceeds a predetermined input current.
Generally, the present invention overcomes the difficulties of the prior art by providing a method for forming an apparatus, comprising the steps of:
selecting a material having a hardness of at least D-50 on a Shore scale or at least A-95 on the Shore scale; and
forming a box made of the material, wherein forming the box includes forming an attachment device within the box for coupling a circuit pattern to the box, and wherein the circuit pattern includes a capacity to process an input electric current having a power of at least 0.1 megawatts.
More specifically, the present invention provides a method for forming an apparatus, comprising the steps of:
selecting an ether-type urethane material having a hardness of at least D-50 on a Shore scale or at least A-95 on the Shore scale; and
forming a box, including forming a base and a cover, wherein the base and the cover are each made of the material, and wherein forming the base includes:
forming an attachment device within the base for coupling a circuit pattern to the base, wherein the circuit pattern includes a capacity to process an input electric current having a power of at least 0.1 megawatts, and wherein the circuit pattern includes a fuse that blows if the input electric current exceeds a predetermined input current;
forming at least one first hole through a wall of the base; and
forming at least one second hole through the wall of the base.
The present invention has the advantage of providing a high impact-resistant box, such as a fuse box, for use with a circuit pattern within the box that is capable of receiving and processing an electrical input current at a power of at least 0.1 megawatts. The box is made of a material having a high impact resistance such that the box enclosure is able to reliably remain intact if impacted by energetic objects, such as products of an explosion from the blowing of a fuse located within the box. The box material is a plastic that has a hardness of at least D-50 on the Shore scale or A-95 on the Shore scale. For D-material and A-material having comparable hardness (e.g., D-50 and A-95), the D-material is preferred because the D-material has a greater tensile strength, tear strength, and elastic restoration capability.
The present invention uses an ether-type urethane material having a hardness of of at least D-50 on the Shore scale. Urethane is relatively inexpensive to use for fabricating the box, because its property of being liquid at room temperature enables it to be used with an open-pour molding process, in contrast with a more expensive process, such as injection molding, that would be used with most other plastics. The material has an especially high impact resistance for the purpose of the present invention, because of an associated high tensile strength, high tear strength, and the ability to be restored to its original length upon release of a force that causes the material to be elongated. The ether-type character of the urethane enables the material to maintain its beneficial properties in the presence of moisture. Moreover, the material is not brittle and offers the added benefit of being able to absorb vibration.
The box of the present invention may be advantageously coupled to a vehicle, such as a railed vehicle, or to a static structure, such as a telephone pole or building.
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Oliva Carmelo
Reichard Dean A.
Schmeiser Olsen & Watts
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