Fluid reaction surfaces (i.e. – impellers) – Protective screen or guard – Water or marine propellers
Reexamination Certificate
1999-12-14
2002-08-27
Look, Edward K. (Department: 3745)
Fluid reaction surfaces (i.e., impellers)
Protective screen or guard
Water or marine propellers
C415S121200, C416S24700A
Reexamination Certificate
active
06439852
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to protective guards for apparatus with moving and/or extreme temperature components and, more particularly, to protective wire guards for rotating fan blades.
BACKGROUND ART
A wide variety of work machines, including construction and excavation work machines, are used for various construction and development purposes. In the operation of these work machines, potentially intense heat is generated as a natural by-product of the drive engine and other mechanisms associated with these work machines. To sustain optimum performance, the engine and other mechanisms are operated within determined temperature limits. Thus, it is necessary to dissipate the heat generated during operation of the drive engine and other mechanisms, and a wide variety of cooling systems have been developed to dissipate heat in these work machines.
Typically, an air circulation device, such as a fan, is installed with a plurality of heat exchanger cores having fins positioned in the path of the airflow from the fan to dissipate the heat generated. To inhibit injury, a low impedance guard preferably covers the fan blades. Known guards utilize a mesh of spaced wires to cover at least the downstream side of the fan and inhibit access to the fan blades. In one mesh arrangement, a plurality of radial wires support a plurality of concentric circular wires which incrementally decrease in diameter toward the center of the fan. Welds are typically used to interconnect the radial wires with the circular wires to form welded joints where the wires intersect.
As the wires are welded together, microscopic cracks are formed in the welds and adjacent wires. Over time, the vibration, heat, and deflection inherent in the operation of the fan and adjacent systems cause the cracks to grow and spread until the welds or the wires themselves are compromised allowing the wires to separate and impair the safety function of the guard. Additionally, the separated wires rattle creating undesirable noise. Thus, the wire guards fail after an undesirably short operational period leading to increased replacement, repair, and maintenance costs.
Other attempts to address these concerns have utilized independent clips to connect the wires, and others have used bendable tabs extending from the guard members. However, the bends in the tabs exhibit failure similar to the welds when exposed to the vibration and deflection inherent in the fan operation, and the use of clips appreciably raises the cost of the guard and allows undesirably high relative movement, which increases noise.
It is therefore desirable to increase the operational life of fan guards, to reduce fan guard maintenance and repair costs, and to attenuate noise emitted by fan guards.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the present invention, a guard for inhibiting access to moving components of a mechanism is disclosed. The guard includes a plurality of substantially rigid support members having support member bodies, a plurality of substantially rigid screen members having screen member bodies, and a plurality of joints between the support members and the screen members, the joints including openings through at least a selected plurality of the plurality of support member bodies and the plurality of screen member bodies and another plurality of the plurality of support member bodies and the plurality of screen member bodies extending through the openings.
In another aspect of the present invention a method of assembling a wire guard including a plurality of first bars defining first recesses, a plurality of second bars, and a plurality of screen members for inhibiting access to moving components of a mechanism is disclosed. The method includes inserting the screen members into the first recesses of the first bars, and attaching the second bars to the first bars to hold the screen members in the first recesses.
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Andriotis John C.
Khoshnevissan Manzar
Miers Bruce W.
Othman Jeffery M.
Blackwell Sanders Peper Martin LLP
Caterpillar Inc.
Look Edward K.
Woo Richard
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