Patent Application
20150114897
Various embodiments of the invention pertain to fluid filters, including for example filters for vehicle oils such as transmission oils.
Vehicle parts such as engines and transmissions are often used with various oils or other internal fluids. Various filters are known to remove contaminants or other materials from the fluids. In the case of transmissions, for example filters having a housing that encloses a filter media such as a felt like media are used, with the fluid passing through the media under pressure or suction applied to the filter on the inlet or outlet side.
When the fluid is at a colder temperature, some fluids become highly viscous and thus may create a large pressure drop compared to warm operation.
Accordingly, some embodiments provide a filter having a fine media and a coarse media, with a bypass of the fine media.
In one aspect, a fluid filter is provided comprising a housing having an inlet and an outlet: and a fine media element disposed in the housing, the fine media element having a fine media and a plurality of apertures therethrough so that all fluid flowing through the filter passes through either the fine media or the apertures.
In another aspect, a fluid filter is provided comprising a housing having an inlet and an outlet, a fine media element disposed in the housing, the fine media element having a fine media and a plurality of apertures therethrough so that all fluid flowing through the filter passes through either the fine media or the apertures, wherein the fine media element is an overmolded pleat pack, and wherein the fine media element has a peripheral flange and the apertures are disposed on the peripheral flange; and a coarse media element disposed in the housing, the coarse media element having a coarse media so that all fluid flowing through the filter passes through the coarse media.
In the following description numerous specific details are set forth in order to provide a thorough understanding of the invention. However, one skilled in the art would recognize that the invention might be practiced without these specific details. In other instances, well known methods, procedures, and/or components have not been described in detail so as not to unnecessarily obscure aspects of the invention.
In the following description, certain terminology is used to describe certain features of one or more embodiments of the invention. Some embodiments will now be described by way of example, with like reference numbers referring to like parts throughout.
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Although the fine filter element 20 and the coarse filter element 40 in this example are both shown as being a pleat pack type, in other examples one or both filter elements 20 and 40 may be of a flat or other type. Also although the fine filter element 20 is shown upstream of the coarse filter element 40 so that the fine filter element 20 is closer to the inlet side of the direction of the flow and the coarse filter element 40 is closer to the outlet side of direction of flow, this arrangement can be reversed to place the coarse filter element 40 upstream.
In operation the apertures 30 can in some examples have some or many advantages. The apertures 30 may be considered in some cases as flow control openings, in that fluid being filtered will flow through them. In cold conditions, when the fluid is more viscous, some or all of the fluid, depending on pressure and viscosity, can flow through the apertures 30 to relieve the pressure drop. In warmer conditions, when the fluid is less viscous, more fluid will tend to flow through the fine media 24. In this example, all fluid always flows through the coarse media 44.
The provision of a plurality of numerous small peripheral apertures 30 can provide a large total bypass area while maintaining a small footprint. For example in same cases a bypass area to outlet area ratio of 1:1 or 1:1.25 may be desired, and this bypass area can be fit conveniently into the periphery of the fine filter element 20. Placing the passive bypass in the form of many small apertures 30 on the periphery of the fine filter element 20 may allow the bypassed fluid to be more evenly distributed around the general flow path of all the fluid, and thus provide a desirable transitional flow characteristic between cold and warm states, as compared to a single large bypass region. Moreover, in the illustrated example the upper and lower housings 12 and 16 retain a compact footprint. As noted above also, many small apertures similar to apertures 30 can be placed in more central rib parts of the fine filter element 20 instead of, or in addition to, apertures 30 around the periphery of the fine filter element 20.
While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications are possible. Those skilled, in the art will appreciate that various adaptations and modifications of the just described preferred embodiment can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.
