Electric heating – Heating devices – Combined with diverse-type art device
Reexamination Certificate
2002-02-07
2004-04-27
Leung, Philip H. (Department: 3742)
Electric heating
Heating devices
Combined with diverse-type art device
C219S635000, C219S639000, C219S537000, C104S279000, C246S428000
Reexamination Certificate
active
06727470
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to railroad track switch heaters and, in particular, to impedance based and other heating systems that provide the desired heating for switches and other railroad components with reduced heating structure that can become damaged or pose hazards in the vicinity of a switch.
BACKGROUND OF THE INVENTION
Railroad track switches typically involve a pair of stationary rails and a pair of switching rails that move between engaged and disengaged positions. In the engaged position, commonly referred to as the “reverse position,” a switching rail abuts the gauge side of a stationary rail, i.e., the side which engages the flange of a train wheel, so as to divert the train wheel from the stationary rail and the corresponding track to another track. In the disengaged position, commonly known as the “normal position,” the switching rail is separated from the gauge side of the stationary rail so that a passing wheel is unaffected by the switching rail.
In order to ensure proper functioning of a railroad switch, it is important that the switching rail and stationary rail make good contact in the engaged position. Accordingly, in cold climates, it is common to heat the rail switch or otherwise guard against build up of ice or snow at the switch, especially at the interface between the gauge side of the stationary rail and opposite side of the switching rail.
It will be appreciated that a malfunctioning switch presents a danger of derailment resulting in severe personal and property damage. Although switches are now normally equipped with sensors to provide advance warning in the event of a potentially malfunctioning switch, switch contact problems are nonetheless a hazard, can result in considerable delay and annoyance, and are a significant burden to the rail transportation system in cold climates. Switch malfunctions also result in loss of track time for cargo and other commerce, thereby adversely affecting profitability.
A number of different types of track switch heaters have been devised including heaters that operate on radiant (e.g., infrared element), convective (e.g., forced air); and/or conductive (e.g., electrical heater element) principles. Among these, certain heaters have relative advantages for particular applications based on efficiency, availability of an appropriate power source at a remote location or other considerations.
However, known track switch heaters are subject to one or more of the following disadvantages. First, some heaters can be damaged or can become worn due to repeated movement of the tracks incident to switching. In addition, some heaters are inefficient due to their reliance on convective or radiant heating. Other heaters are inefficient due to use of a small surface area for conductive heat transfer or uneven heat distribution across the heat transfer surface. In this regard, rounded heater element housings have a limited area of direct thermal contact and, in operation, such contact may be further limited if the housing becomes disfigured due to thermal warping or impact.
SUMMARY OF THE INVENTION
The present invention is directed to various implementations of a railroad track switch heating system that reduce or eliminate the need for heater elements or other heater components protruding from rail surfaces in the area of the switch. It has been recognized that such protruding elements are a common source of failures or malfunctions of heating systems. In particular, as noted above, the track switch environment is a rugged environment where protruding elements may be damaged by operation of the switch. In addition, such elements may be damaged during servicing of the track. For example, the track bed may be serviced periodically by machinery that grips and lifts the track or ties so that the bedding material can be restored. Such equipment can damage protruding elements. Moreover, the track itself may occasionally be manipulated by servicemen installing or repairing components related to track signaling and the like. Again, protruding elements are subject to inadvertent damage during such servicing. Protruding elements may also become warped, bent, or otherwise fail to maintain good thermal contact with the track, resulting in heating inefficiencies. In this regard, track surfaces may include raised lettering and other topological features that can interfere with good thermal contact between a rail and an external heating element. Such problems are reduced or eliminated by the present invention.
In accordance with the present invention, a heating system for heating a section of railroad track is disclosed. The heating system includes a power source for providing electrical power, a first heater assembly associated with a railroad structure located in the section of railroad track that is to be heated, wherein the heater assembly has at least a first heater structure which does not substantially protrude above the surface of the railroad structure; an electrical interface for applying an electrical potential across the heater structure in order to produce a current within the structure and control means to control the heat applied to the section of railroad track. Depending on the application, the power source may be, for example, a line of a power grid, where available, or a generator system, regardless of the source, the electrical power may be provided via either alternating current (AC) or direct current (DC) for use in the heating system. The control may include a processor for controllably delivering electricity to the electrical interface (e.g., via electrical leads) and a transformer to provide an electric signal suitable for heating the track without creating undue hazards for workmen or others. The controller may be associated with a thermal sensor to provide feedback regarding the temperature of the track. Feedback may also be provided regarding ambient conditions so as to provide an indication of potential ice buildup in the vicinity of the switch.
In a first aspect of the present invention the system's heater assembly has a heater structure at least partially embedded within a railroad structure located in the section of the railroad track to be heated. In this regard, the heater structure may comprise some sort of separate heating element that is embedded within a railroad structure located in the section of railroad to be heated. Again, this embedded heating element will be substantially non-protruding above the surface of the railroad structure in which it is embedded.
Various refinements exist to the elements included in the first aspect of the present invention. For example, in one embodiment of the first aspect of the present invention, the heater structure is embedded in a railroad tie for placement beneath and interconnection with the track rails of the railroad section to be heated. The embedded heater structure is used to provide thermal energy to the track rails and the general area surrounding the track rails to clear snow and ice while not substantially protruding above the surface of the railroad tie. In many cases, concrete, metal or other prefabricated railroad ties are being used in place of traditional ties formed from timbers. The construction process for such ties (as well as conventional timber ties) can readily be adapted so that a heater structure may be embedded in a surface of these ties (e.g., an upper surface of the tie adjacent to the rail track attachment locations). Such heater structures may extend across the width of the tie or be exposed only in the area of the track rail. Preferably, the heater structure is embedded so that it is substantially flush with an upper surface of the tie. In this regard, one surface of the heater structure may be exposed on the tie's surface such that the heater is disposed between the tie and the track rail upon assembly to increase heat transfer therebetween.
In another embodiment of the first aspect of the present invention, the heater assembly is embedded or interconnected with the track rail such that the
Fastrax Industries, Inc.
Leung Philip H.
Marsh & Fischmann & Breyfogle LLP
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