Disposable spin-on type oil filters

Claim 1

A disposable spin-on type oil filter comprising: a cylindrical closed-ended filter housing, one end closure of which comprises a heavy-gauge base plate provided in its central portion with an inturned tubular neck whose bore serves as an oil outlet passage, and radially outwardly therefrom with a plurality of through-holes serving as oil inlet openings; a filter element enclosed within the housing and including an annular body of a suitable oil filtering material disposed about a perforated center tube; a bypass valve unit interposed between said base plate and the filter element and supporting the latter spaced from the baseplate inner surface and with its center tube co-axial with and in fluid communication with the bore of said tubular neck; said bypass valve unit normally establishing an oil flow path extending from said oil inlet openings to and thence radially inwardly through the annular body of filtering material to the center-tube bore and thence axially to and outwardly through the neck bore and being also effective to establish a bypass oil flow path extending substantially direct from said oil inlet openings to said center-tube and neck bores, said unit including a tubular adapter bushing closely encircling said tubular neck and having one end extending to said base plate and being provided at its other end with a radial outwardly extending flange of substantial width including inner, intermediate and outer radial-width portions, said intermediate radial-width portion having a plurality of circumferentially spaced-apart oil bypass openings formed therein and which are disposed on a circle such that they are adapted to open to the bore of the center tube, a generally planar valve annulus of flexible material having radial width substantially equal to the full radial width of said adapter-bushing flange and being disposed generally flush against the relatively upper face of said flange, and spring means reactive against at least the inner radial-width portion of said adapter-bushing flange and normally maintaining the corresponding inner radial-width portion of the valve annulus seated thereon as effects closing of said bypass openings to oil flow therethrough, said inner radial-width portion of the adapter bushing flange being so fashioned that said valve annulus normally seats thereon as aforesaid with line contact only, said spring means including an open-ended cylindrical spring-retaining cup whose body extends into and is closely fitted to the filter-element center tube and which terminates at its relatively lower end in a radial outwardly extending filter-element supporting flange whOse outer-edge portion is bent overthe outer radial-width portions of both the valve annulus and the adapter-bushing flange and clinched tight against the relatively under face of the latter, thereby clamping the outer radial-width portion of said valve annulus to the corresponding outer radial-width portion of said adapter-bushing flange, the arrangement being such that said bypass valve unit provides an annular seat for the filter element and as a means for bypassing the incoming oil around the filter element in the event of oil pressure in the closed-ended housing exceeding the force which the spring means exerts on the inner-radial width portion of said valve annulus as aforesaid; anti-drainback valve means secured in operative position within thE filter housing by said bypass valve unit; said anti-drainback valve means comprising a preform of rubber or rubber-like material having the configuration of a truncated cone which is clampingly secured along its smaller-diameter end to the bottom end of the filter element adjacent its center tube by said bypass valve unit and which extends relatively downwardly-outwardly therefrom over a substantial radial width portion of the base-plate inner surface and which encircles the inturned tubular neck and in which the oil-inlet openings are provided as aforesaid, said radial-width portion of the base plate being defined along its outer perimeter by a circular ridge-like formation, the larger-diameter end portion of the preform overhanging said circular ridge-like formation by a small radial amount and pressing thereagainst throughout its full circumference.