Method and apparatus for filtering air passages in an alternator

A filter to clean the air entering an alternator in a vehicle used in a dirty environment such as a crop harvesting machine includes a mesh filter which is coupled to an air intake of the alternator. The filter is constructed of a mesh material which is flexible and includes relatively small apertures. The apertures prevent chaff and other extraneous material from entering the alternator, while allowing air to flow freely into the alternator, preventing overheating. The flexible mesh sleeve can be vibrated during operation, as, for example, by the flow of air from the engine fan, to provide a self cleaning function in which the vibration causes extraneous material to be shook from the filter.

BACKGROUND OF THE INVENTION

This invention relates generally to alternator filters and, more particularly, concerns self-cleaning alternator filters for use in dirty environments.

Alternators are used to supply electrical energy to an array of vehicles including rugged off-road construction and agricultural equipment. When used in the dirty environments associated with this type of equipment, however, the cooling air passages in the alternator can become blocked by foreign matter, causing the alternator to overheat, decreasing the efficiency and output of the alternator, and ultimately resulting in the failure of the alternator. Moreover, in these types of vehicles, the alternators are typically located at fairly inaccessible positions, and therefore are both time consuming and inefficient to remove and repair.

To limit overheating problems caused by clogged cooling passages, therefore, alternators operated in “dirty” environments are typically equipped with screens designed to prevent the entrance of foreign matter into the alternator cooling passages. While these screens are useful in limiting blocking of the alternator, after the vehicles have been used for a number of hours the screens themselves often become clogged, thereby cutting off all air flow to the alternators cooling passages. The result of the clogged screen is substantially the same as the clogged passages, resulting in overheating and eventual failure of the alternator as discussed above. While it is possible to clean the stationary alternators, again, the alternators are typically located at fairly inaccessible positions within the vehicle, and therefore it is both time consuming and inefficient to clean the screens manually.

A need remains, therefore, for a filtering system for an alternator for off-road vehicles and vehicles used in dirty environments.

BRIEF SUMMARY OF THE INVENTION

In one aspect the present invention provides a method for filtering air entering an alternator. A filter support is coupled to an air intake of the alternator extending away from the air intake, and an elongate flexible mesh sleeve is coupled to the filter support such that the elongate flexible mesh sleeve encloses the air intake. The mesh is sized and dimensioned to limit entry of extraneous material to the alternator. The flexible filter is vibrated in operation to force filtered material loose from the filter sleeve, thereby limiting or preventing clogging of the filter, and maintaining a flow of air through the alternator during use. In one embodiment of the invention, for example, the vibration of the mesh filter is provided by air flow from an engine fan in the engine compartment.

In another aspect of the invention, a self-cleaning filter for an alternator air intake is provided. The filter comprises an elongate filter support sized and dimensioned to be received on the alternator air intake and extending away from the air intake and an elongate flexible sleeve having an open end sized and dimensioned to be received on the elongate support and over the air intake of the alternator, and an opposing closed end. The elongate flexible sleeve is constructed of a mesh filter material having apertures which are sized and dimensioned to limit debris from entering the air intake.

In yet another aspect of the invention, a self-cleaning filter assembly for use in an off-road vehicle is provided. The self-cleaning filter comprises an alternator including a fan for drawing air into the alternator, the alternator having an air intake side from which air is drawn into the alternator, and an air outtake side from which air is expended from the alternator. A filter support is coupled to the air intake side, and extending from the air intake side to support a flexible mesh filter. The flexible mesh filter is coupled to the air intake side of the alternator to filter air entering the alternator, and is provided over the filter support wherein the filter support prevents the flexible mesh filter from being drawn into the alternator.

These and other aspects of the invention will become apparent from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention and reference is made therefore, to the claims herein for interpreting the scope of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures and more particularly toFIG. 1an alternator assembly14constructed in accordance with the present invention is shown. The alternator assembly14comprises an alternator10to which a cover12is coupled with threaded fasteners16. The cover12includes an air intake port18to which a filter support20is coupled. A flexible elongate mesh sleeve22is positioned over and coupled to the filter support20by means of a clamp24sized and dimensioned to extend over the air intake18and the elongate mesh sleeve22and to lock the sleeve22in place. The alternator10includes an internal fan (not shown) which draws air through an air intake side of the alternator10behind the air intake port18and into the alternator10to cool the internal components during operation. Air is then expended out of the opposing side of the alternator, out of an outtake side of the alternator10. As described below, in operation, the flexible elongate mesh sleeve22filters chaff and other material which would otherwise enter the alternator10. The sleeve22is self-cleaning, as vibrations in the engine caused, for example, by the engine fan, cause the flexible sleeve to “wave” in the wind, or vibrate, shaking collected chaff from the sleeve22, also as described below.

Referring now toFIG. 5the elongate mesh sleeve22comprises a first open end26sized and dimensioned to extend around the air intake18ofFIG. 1and an opposed closed end28. The elongate mesh sleeve22is constructed of a material which can be, for example, a flexible mesh or screen including a plurality of apertures which are sized and dimensioned to prevent extraneous chaff and other material from entering the air intake18of the cover12in the alternator assembly14, and thereby to allow air to enter while preventing chaff and other extraneous material from entering the alternator10. The elongate mesh sleeve22is constructed to be as long as possible, while allowing for placement in the engine compartment as discussed below. The greater the number of square inches in the sleeve22, the more effective the sleeve22is at filtering materials. Furthermore, as the size increases, the shaking or vibrating of the screen increases, resulting in improved cleaning of the screen.

The flexible mesh sleeve22is preferably constructed of a material selected to withstand underhood operating temperatures, which are typically in the range of 100 to 180° F., and which is sufficiently flexible to be vibrated by forces within the engine compartment to cause extraneous material to be vibrated or “shook” from the sleeve. Although a number of different types of material could be used for producing the sleeve22, in a preferred embodiment, the mesh is constructed of a polyester or nylon material. To provide appropriate filtering the mesh will include a hole size in a range extending from about 25 to 500 microns, and preferably in the range extending from 100 to 25 microns. The thread diameter is selected to be small enough of the screen material to flex, but large enough to prevent the screen from breaking. A thread diameter in the thousandths of inches, for example, has been shown experimentally to be appropriate for the application. These parameters have been shown experimentally to provide a sufficiently small hole size to filter most chaff from entering the alternator, while providing efficient air flow, and sufficient flexibility to provide the self-cleaning function. However, these parameters can be varied depending on the level of vibration, materials selected, and other variables.

Referring now toFIGS. 2–4an exploded view of a first embodiment of an assembly14constructed in accordance with the present invention is shown. The filter assembly14comprises the cover12which includes mounting tabs30,32, and34including apertures for receiving threaded fasteners16coupling the cover12to the alternator10as shown inFIG. 1. As described above, the alternator cover12includes an air intake port18which is substantially cylindrical in shape and has an open end38through which air can flow toward the alternator10. Although shown as including a cover12, the filter assembly can also include a support20coupled directly to the air intake side of the alternator10.

Referring now toFIG. 2, the filter support20can be constructed of a malleable wire material and includes a connector end42in the form of a circular connector sized and dimensioned to be received on the air intake18. From the connector end42, the wire support extends away from the cover12, through an elongate section45, and then loops to form a hook at the opposing end44. The length of the elongate section45to extend substantially from the open end26to the closed end28of the filter sleeve22, and therefore to maintain the sleeve22extending away from the cover12, preventing the sleeve22from being drawn into the alternator10.

Referring now toFIG. 3, an alternative embodiment of the filter assembly14is shown. Here, the filter support20is a coiled spring sized and dimensioned to be coupled to the air intake port18. The coiled spring construction both prevents the sleeve22from being pulled back into the alternator10, as described above, and can further enhance vibration of the sleeve. Referring now toFIG. 4, an alternative, preferred embodiment of a filter support20as shown. Here the filter support20is generally U-shaped and is sized and dimensioned such that the legs of the support20fit within the inner circumference of the air intake18. The filter support20can include one or more aperture21which can receive a threaded fastener, rivet or other fastening devices for fastening the filter support20to the cover12. Alternatively, the legs of the U-shaped bracket can be snap fit into the air intake port18. As shown inFIG. 4, the filter sleeve22can be dimensioned for the selected support. Here, for example, the sleeve22tapers as it approaches the closed end such that the closed end28is sized and dimensioned to fit snuggly over the support20.

Although a support member20having a specific construction has been described, various methods of coupling the filter mesh screen22to the cover12will be apparent. Support members20can be provided, for example, in the form of various types of sheet metal constructions could be formed as part of the cover12, or stiff, flexible materials which prevent vibrations. Additionally, as described above, although the alternator assembly14is shown to include a cover12, the alternator10can also be used without a cover. In this application the filter support member can be coupled directly to the alternator10, and the filter sleeve22and associated clamp24are sized and dimensioned to fit over the outer circumference of the alternator10, or over a smaller air intake oven, depending on the construction of the alternator.

Referring now toFIG. 6, the alternator assembly14is shown as installed in the engine compartment48of an agricultural combine, crop harvesting machine, or other vehicle used in a “dirty” environment in which particulate matter capable of clogging the alternator10is found. The engine compartment48typically includes an engine fan46which provides an air flow through the engine compartment48.

During operation, as the internal fan (not shown) of the alternator10pulls air into the intake side of the alternator10, chaff and other material collects on the elongated mesh sleeve22. The engine fan46blows air through the engine compartment48vibrating the filter sleeve22such that the collected material can be dislodged from the sleeve22, thereby providing the self-cleaning function, limiting the possibility of clogging the filter, and decreasing the need for maintenance. During operation, the filter support member20prevents the sleeve22from being pulled toward the air intake port18and drawn into the alternator10by the operation internal fan.

Although, as shown here, the filter sleeve22is caused to vibrate by the engine fan and related engine compartment vibrations, the sleeve could also be vibrated in a number of other ways. For example, mechanical devices, including springs, mechanical arms, or other devices, could be provided to shake and/or apply intermittent forces to the filter sleeve22to shake the accumulated particulate matter from the filter sleeve22. Furthermore, while a specific filter support20is shown and described, a number of different types of supports could be used, as described above. The filter support20and filter sleeve22, furthermore, can be provided either in conjunction with a cover12or directly on the intake side of the alternator10.

It should be understood therefore that the methods and apparatuses described above are only exemplary and do not limit the scope of the invention, and that various modifications could be made by those skilled in the art that would fall under the scope of the invention. To apprise the public of the scope of this invention, the following claims are made: