Liquid purification or separation – Processes – Separating
Reexamination Certificate
1997-10-16
2001-05-08
Savage, Matthew O. (Department: 1723)
Liquid purification or separation
Processes
Separating
C210S443000, C210S497300, C210SDIG009, C156S069000, C156S073100
Reexamination Certificate
active
06228274
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to filtering devices. In particular, the present invention relates to a renewable spin-on type filter including a high strength plastic housing.
2. Discussion of Background
Spin-on, twist-on type filters are used in numerous liquid and pneumatic applications throughout the agricultural, mobile, commercial and industrial markets. The housing or can for most spin-on disposable filters are manufactured by deep-draw forming of malleable materials such as aluminum. This technique limits the structural capabilities of current spin-on and twist-on type disposable products to the production capabilities of the metal forming industry and to the molecular characteristics of a limited number of specific malleable metals. Prior art disposable filters use a stamped steel or cast cover plate to secure the housing or can to a mounting and distribution head assembly. This plate typically has a threaded center hole and is spot welded and/or crimp sealed to a deep-drawn can. The purpose of the cover plate is to provide a mounting site that contains sufficient strength to allow operation of the filter at the required pressure rating. These prior art techniques for sealing and connecting the can to the plate, plus the structural limits of thin gauge malleable metals, restrict the application and uses of prior art spin-on, twist-on disposable filters. Recently new high pressure, high burst strength disposable filter housings with burst pressure ratings in the 1000 psi range have been developed for some narrowly defined markets and applications. However, even these newer high-strength filters remain applicationally limited because of their continued use of deep-drawn metal cans.
The filter media used in the prior art are usually paper products that are flexible and flimsy. As a result of their flexible and flimsy characteristics these filters often are not properly secured in place within the housing or can during the assembly of the filter. By some accounts 50% of current commercially available oil filters are defective and thus do not perform up to specification. Also, prior art paper filters often develop rips or tears during use. Such defects are not visible and the filter is used for its normal use period during which improperly filtered oil is re-circulated through the engine. Serious damage to the engine can result.
Once these disposable filters have served their purpose and are in need of replacement, the filter is removed from the vehicle or machine and the remaining filtrate, usually oil, is drained and replaced. Thereafter, the filter is compacted and disposed of in accordance with industry practice. The impact on the environment from the disposal of used filters and oil cannot be overstated when the variety of industrial and consumer applications that employ disposable filters, as well as the frequency with which they are replaced, is considered. The enormity of this situation and its impact on the environment can be appreciated when it is realized that there are currently about 180,000,000 vehicles in the United States for which it is recommend that the filter and oil be change every 3,000 miles. About 400,000,000 oil filters are manufactured in the U.S. each year, of which less than 25% are properly recycled. The remaining, which retain some oil, are disposed of and this used oil enters the environment. Even properly drained oil filters retain up to 8 ounces of used oil. It is estimated that the result of recycling would result in the recovery of more than 17,000,000 gallons of oil. If properly processed this oil could be reused.
Therefore, there exists a need for a twist-on filter that is renewable, which would support and encourage the recycling of used oil and reduce environmental liability.
SUMMARY OF THE INVENTION
According to its major aspects and briefly stated, the present invention is a renewable twist-on filter comprising a polymeric, unitary housing that is open at the top and includes a filter element adhesively secured within the interior of the housing. In one embodiment of the invention the housing is fitted with an external male thread, allowing its removable attachment to a head distribution assembly. This external male thread is disclosed as being cut or molded into the polymeric material of the housing, however a metallic member having machined threads could be secured to the housing by welding or bonding. Likewise the threaded member contained on the head distribution assembly can be either cut or molded into the polymeric material or a metallic member can be provide into which threads are machined. The advantage of utilizing metallic threaded members being that they are more durable and will have a longer service life.
In another embodiment of the invention the end cap or top member of the housing is provided with a female threaded center section for removably attaching the filter to the head distribution assembly. As stated above with regard to the earlier discussed embodiment the threaded members can either be formed in the polymeric material or threaded metallic members can be utilized. In this embodiment the end cap or top member is plastic welded to the hollow polymeric container to thus provide a closed housing having an interior chamber. Thus the end cap or top member is fused to the hollow polymeric container and this assembly now function as a closed housing having an interior chamber within which is securely attached the filter media. It should be noted that although this embodiment discloses a housing formed from a cup shaped member that is closed by a disc shaped end cap, the end cap need not be disc shaped but rather could be a cup shaped top member. It should also be noted that although the hollow polymeric container or cup shaped member is disclosed as being a unitary cast part it could also be fabricated from a section of polymeric tube having a molded bottom end member bonded or welded thereto. The essential feature being that the components from which the hollow housing are formed are welded together to form a closed housing having an interior chamber within which is securely attached the filter media. The filter is secured by adhesive at both ends within the housing such that the filter is immovable relative to the housing. In this embodiment the end cap or top member functions as a mounting means for the filter as well as an end cap or top member for the housing. The bottom of the filter is secured to the bottom or closed-interior-end of the housing by an adhesive material. The top of the filter is bonded within a circular groove formed in the inner surface of the end cap or top member. The filter thus divides the interior chamber of the housing into an inlet section and a discharge section. The filter medium may be any medium commonly employed in the art that is capable of being cleaned and subsequently reused.
In the preferred embodiment the filter is formed from a flat piece of metal mesh material cut to a shape having a pair of edges that when joined, by a weld or encapsulated by adhesive, cause the flat piece of material to assume the shape of a cone. The metal mesh material is folded or pleated radially prior to joining the edges such that after the edges are joined the filter is in the shape of a truncated cone having continuous top and bottom edges. The pleats extend from the top continuous edge to the bottom continuous edge. The surface area of the filter is greatly increased by this filter design.
When the filter requires cleaning, it is removed from the distribution head of the vehicle or machine, and the excess fluid contained therein is drained out. This small amount of fluid that is drained from the filter can be easily disposed of in a manner that is not detrimental to the environment. Thereafter, the filter is back flushed using a cleaning solution. Once cleaned, the filter may be dried prior to reuse by allowing it to stand for a period of time or by blowing a drying gas therethrough. As a result of using the highly efficient and reli
Deibel Richard J.
Dugan Patrick M.
Brinks Hofer Gilson & Lione
Dei-Tec Corporation
Savage Matthew O.
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