GB1603858A - Filter cartridges - Google Patents

Description

(54) IMPROVEMENT IN FILTER CARTRIDGES (71) We, FRAM CORPORATION, a corporation organised and existing under the laws of the State of Delaware, United States of America, of 105 Pawtucket Avenue, East Providence, Rhode Island, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention is concerned with anti-drain performance in replaceable filter cartridges, for example for use in the filtering of oil in motor vehicles.

We describe below a preferred embodiment of valve assembly constructed in accordance with this invention, being provided with location means adapted to locate the valve assembly upstream of, and across the flow of filtered fluid to, the outlet of a replaceable filter cartridge of the kind having a housing of generally closed cylindrical form provided in one axial end with a central outlet for filtered fluid and one or more inlets for fluid to be filtered spaced radially outwardly of said outlet. The valve assembly has a valve in the form of a single moveable component formed of an elastomeric material and relying only upon elastic properties of the moveable component to provide sealing against a valve seat to prevent drain back. The invention also extends to a replaceable filter certridge incorporating such a valve assembly.

In order that the present invention may be best understood, we shall first describe, with reference to Figures 1, 2 and 3 of the accompanying drawings, three typical methods currently in practical use for providing antidrain valve facilities in replaceable filter cartridges. Figure 4 shows an axial sectional view of an embodiment of filter cartridge constructed in accordance with the present invention.

Figures 1, 2 and 3 are partial views, in axial section, of three prior art replaceable filter cartridges, each having a housing 1 of generally closed cylindrical form provided with a central outlet 2 in one axial end 3, which outlet Is threaded internally for mounting the cartridge to a permanent fitting, for example on a motor car. Radially outwardly of outlet 2 are provided a plurality of similar inlet apertures 4 (only one shown here). Oil to be filtered enters the cartridge at the inlets 4 and passes by outside-in flow through an annular filter element 5 before arriving at outlet 2. In order to prevent oil from draining out of the filter cartridge when the vehicle is stationary it is customary to provide an anti-drain system which in the most-widely used form consists of a central weir tube 6 which will serve to reduce the quantity of oil draining through the outlet, and an anti-drain valve assembly located adjacent the inlets in an effort to prevent oil from flowing back therethrough and out of the cartridge.

The anti-drain valve assembly commonly takes one of three alternative forms. A special rubber moulding or diaphragm may be employed, as in Figure 1. Alternatively, a thin flexible and readily deflectable diaphragm 8 may serve as the valve member; but in this case biasing means, for example in the form of a maze spring 9 (Figure 2) or a combination of plate 10 and coil spring 11 (Figure 3), must be used to bias the valve member towards the inlet apertures.

None of these prior art systems is entirely satisfactory. Furthermore, they make a significant contribution to the total cost of the cartridge. Even with their adoption, leakage will still tend to occur from the minute gaps between the main axial end plate 12 and auxiliary plate 13, which is seamed to the cylindrical wall of the housing 1 and serves both to retain main plate 12 in position and to mount an annular gasket 14, unless such gaps are sealed by another gasket or sealing compound at additional cost. Since the diaphragms 7 or 8 are exposed to unfiltered fluid, their surfaces are subject to contamination. Small amounts of grit or of fibrous material lodged beneath the diaphragm are sufficient to render the anti-drain valve completely ineffective. Even if the prior art systems operate exactly as intended, draining of the space within the weir tube 6 will leave a substantial void within the filter cartridge consisting of the space above the level of the lip 15 of the weir tube and in the interior of the weir tube itself. The total volume of the void will also depend upon the particular angle of inclination of the filter cartridge to the vertical. The significance of the void, however, is that when the engine starts again important parts such as engine bearings will be starved of lubricating oil while the void is being filled.

The larger the void, the longer will the bearings have to run without oil being supplied.

We have now found that these problems can generally be avoided by the expedient of placing a simple non-return valve immediately upstream of the outlet. No anti drain valve assembly is then required at the inlets, neither is a weir tube required. Moreover, as will be explained below with reference to Figure 4, the valve assembly may be extremely simple in construction.

The preferred embodiment of filter cartridge constructed according to the present invention and shown in Figure 4 comprises a housing 1 of generally cylindrical form and provided in one axial end with a central outlet 2 and one or more (preferably, a plurality of) inlets 4 spaced radially outwardly ot the central outlet, all as in the prior art arrangements. Filter means of any convenient form - here an annular filter element 5 - is provided within housing 1 to filter oil as it passes from the inlets to the outlet. A non-return valve assembly 16 is located immediately upstream of and across the flow to outlet 2. Valve assembly 16 has a twopart valve housing 17, 18 formed of pressed sheet metal or other suitable material located in position between one axial end of the filter element 5 and main end plate 12 and firmly held in such position by the biasing force of a retainer spring 19 at the opposite end of the element 5. The internally threaded stub pipe 20 formed integrally with plate 12, and which forms the outlet, is received within central aperture 21 of housing part 17. The other housing part 18 has a one-piece valve member 22, suitably a disc formed of an elastomeric material such as natural or synthetic rubber or a suitable plastic, for example polyurethane, which is joined to the centre of housing part 18 as by a rivet 23 or other connection means.

About the centre of housing part 18 are provided a plurality of apertures 24, radially outwardly of which is an annular valve seat 25.

The illustrated valve assembly relies only upon the elastic properties of the valve member 22, which seek to return it from its deformed stressed condition to a flat disc, to provide sealing against valve seat 25 to prevent drain back.

In theory, a valve having a similar function could be provided in the form of a coil spring and flat disc, but in view of the vagaries of spring manufacture and furnish together with the need for substantially perfect flatness of valve and seat and unblemished surface of the disc in such a spring and disc arrangement, we consider the use of a one movable component, elastomeric valve member, assembly described and which is in accordance with the present invention to be both more reliable and less expensive than the disc and spring arrangement which is outside the scope of this invention.

Closure of the non-return valve in our arrangement when the engine stops, prevents atmospheric pressure appearing via the outlet to act upon oil in the cartridge. Oil in the lubricating system will consequently tend not to drain back through the inlets, then via the invariably narrow porting of the oil pump and thence to the sump, or through unsealed leakage paths, when the engine is stationary.

Our experiments show that the filter cartridge remains essentially full of oil. Furthermore, since the valve is on the 'clean' rather than on the 'dirty' said of the filter element, the problem of contamination thereof is substantially reduced.

WHAT WE CLAIM IS: 1. A valve assembly provided with location means adapted to locate the valve assembly immediately upstream of, and across the flow of filtered fluid to, the outlet of a replaceable filter cartridge of the kind having a housing of generally closed cylindrical form provided in one axial end with a central outlet for filtered fluid and one or more inlets for fluid to be filtered spaced radially outwardly of said outlet, the valve assembly having a valve in the form of a single moveable component formed of an elastomeric material and relying only upon elastic properties of the moveable component to provide sealing against a valve seat to prevent drain back.

2. A valve assembly according to claim 1, including a valve housing, and wherein said single moveable component consists of a disc of elastomeric material, an annular valve seat for said disc being provided on an internal wall of said housing and the centre of said disc being joined to said housing such that the disc is elastically deformed and the elastic forces in the disc serving to bias it against the valve seat thereby to close a plurality of inlet openings to the housing which openings are located intermediate the valve seat and the centre of the disc.

3. A valve assembly substantially as hereinbefore described with reference to and as shown in Figure 4 of the accompanying drawings.

4. A replaceable filter cartridge comprising: a housing of generally closed cylindrical form provided in one axial end with a central outlet and one or more inlets spaced radially outwardly thereof; filter means located within the housing to filter fluid as it passes from the inlet(s) to the outlet; and a valve assembly located immediately upstream of, and across the flow of filtered fluid to, the outlet and having a valve in the form of a single moveable component formed of an elastomeric material and the valve assembly relying only upon elastic properties of the moveable component to provide sealing against a valve seat to prevent drain back.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. of inclination of the filter cartridge to the vertical. The significance of the void, however, is that when the engine starts again important parts such as engine bearings will be starved of lubricating oil while the void is being filled. The larger the void, the longer will the bearings have to run without oil being supplied. We have now found that these problems can generally be avoided by the expedient of placing a simple non-return valve immediately upstream of the outlet. No anti drain valve assembly is then required at the inlets, neither is a weir tube required. Moreover, as will be explained below with reference to Figure 4, the valve assembly may be extremely simple in construction. The preferred embodiment of filter cartridge constructed according to the present invention and shown in Figure 4 comprises a housing 1 of generally cylindrical form and provided in one axial end with a central outlet 2 and one or more (preferably, a plurality of) inlets 4 spaced radially outwardly ot the central outlet, all as in the prior art arrangements. Filter means of any convenient form - here an annular filter element 5 - is provided within housing 1 to filter oil as it passes from the inlets to the outlet. A non-return valve assembly 16 is located immediately upstream of and across the flow to outlet 2. Valve assembly 16 has a twopart valve housing 17, 18 formed of pressed sheet metal or other suitable material located in position between one axial end of the filter element 5 and main end plate 12 and firmly held in such position by the biasing force of a retainer spring 19 at the opposite end of the element 5. The internally threaded stub pipe 20 formed integrally with plate 12, and which forms the outlet, is received within central aperture 21 of housing part 17. The other housing part 18 has a one-piece valve member 22, suitably a disc formed of an elastomeric material such as natural or synthetic rubber or a suitable plastic, for example polyurethane, which is joined to the centre of housing part 18 as by a rivet 23 or other connection means. About the centre of housing part 18 are provided a plurality of apertures 24, radially outwardly of which is an annular valve seat 25. The illustrated valve assembly relies only upon the elastic properties of the valve member 22, which seek to return it from its deformed stressed condition to a flat disc, to provide sealing against valve seat 25 to prevent drain back. In theory, a valve having a similar function could be provided in the form of a coil spring and flat disc, but in view of the vagaries of spring manufacture and furnish together with the need for substantially perfect flatness of valve and seat and unblemished surface of the disc in such a spring and disc arrangement, we consider the use of a one movable component, elastomeric valve member, assembly described and which is in accordance with the present invention to be both more reliable and less expensive than the disc and spring arrangement which is outside the scope of this invention. Closure of the non-return valve in our arrangement when the engine stops, prevents atmospheric pressure appearing via the outlet to act upon oil in the cartridge. Oil in the lubricating system will consequently tend not to drain back through the inlets, then via the invariably narrow porting of the oil pump and thence to the sump, or through unsealed leakage paths, when the engine is stationary. Our experiments show that the filter cartridge remains essentially full of oil. Furthermore, since the valve is on the 'clean' rather than on the 'dirty' said of the filter element, the problem of contamination thereof is substantially reduced. WHAT WE CLAIM IS:

1. A valve assembly provided with location means adapted to locate the valve assembly immediately upstream of, and across the flow of filtered fluid to, the outlet of a replaceable filter cartridge of the kind having a housing of generally closed cylindrical form provided in one axial end with a central outlet for filtered fluid and one or more inlets for fluid to be filtered spaced radially outwardly of said outlet, the valve assembly having a valve in the form of a single moveable component formed of an elastomeric material and relying only upon elastic properties of the moveable component to provide sealing against a valve seat to prevent drain back.

2. A valve assembly according to claim 1, including a valve housing, and wherein said single moveable component consists of a disc of elastomeric material, an annular valve seat for said disc being provided on an internal wall of said housing and the centre of said disc being joined to said housing such that the disc is elastically deformed and the elastic forces in the disc serving to bias it against the valve seat thereby to close a plurality of inlet openings to the housing which openings are located intermediate the valve seat and the centre of the disc.

3. A valve assembly substantially as hereinbefore described with reference to and as shown in Figure 4 of the accompanying drawings.

4. A replaceable filter cartridge comprising: a housing of generally closed cylindrical form provided in one axial end with a central outlet and one or more inlets spaced radially outwardly thereof; filter means located within the housing to filter fluid as it passes from the inlet(s) to the outlet; and a valve assembly located immediately upstream of, and across the flow of filtered fluid to, the outlet and having a valve in the form of a single moveable component formed of an elastomeric material and the valve assembly relying only upon elastic properties of the moveable component to provide sealing against a valve seat to prevent drain back.

5. A replaceable filter cartridge according to

claim 4, wherein the valve assembly has a valve housing, and the single moveable component consists of a disc of elastomeric material, an annular valve seat for said disc being provided on an internal wall of said valve housing and the centre of said disc being joined to said valve housing such that the disc is elastically deformed and the elastic forces in the disc serving to bias it against the valve seat thereby to close a plurality of inlet openings to the valve housing which openings are located intermediate the valve seat and the centre of the disc.

6. A replaceable filter cartridge according to claim 5, wherein the valve housing has an outlet spaced along the axis of the valve seat, the means defining the said valve housing outlet being arranged to embrace a stub pipe forming the said central outlet of the cartridge.

7. A replaceable filter cartridge substantially as hereinbefore described with reference to and as shown in Figure 4 of the accompanying drawings.