GB1589513A - Oil filters - Google Patents

Description

(54) IMPROVEMENTS IN OIL FILTERS (71) We,Wipc DEVELOPMENT LIMITED, a British Company of London Road.

Buckingham MK18 1 BH, 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: The present invention is concerned with oil filters of the kind in which the filter medium is permanently enclosed in a shell or canister. When such a filter needs replacing the entire unit is discarded.

The aim of the present invention is to pro- vide a design of filter unit which is simple and inexpensive to manufacture.

According to the present invention there is provided an oil filter unit comprising a canister with bottom and side walls, a top plate, an annular filter element in the canister one end of the filter element abutting the bottom wall of the canister, a moulding which is fitted over the end of the filter element remote from the bottom wall and has an antidrain flap valve which engages the side wall of the canister and a pressure relief by-pass valve, the moulding, anti-drain flap valve and the seat of the pressure relief by-pass valve being formed as a single part.

Embodiments of the invention will now be described with reference to the drawings accompanying the complete specification, of which: Figure 1 is a side elevation of a filter unit; Figure 2 is a plan view from below of the filter unit of Figure 1; Figure 3 is a plan view from above of the filter unit of Figures 1 and 2; and Figure 4 is a vertical section taken on the line IV-IV of Figure 3 and with reference to the accompanying drawings of which: Figure 5 shows a detail of a modification of the filter unit of Figures 1 to 4.

In the drawings a disposable full-flow canister oil filter unit 10 is shown. The unit comprises a metal canister 11 having a side wall 12 which is cylindrical for most of its length but has, at its lower end as seen in Figure 1, a portion 13 which is faceted to provide a grip for unscrewing the canister from the engine block. The canister is closed at its lower end by an integral end wall 14 which is shaped, by pressing, to form an annular recess 15 spaced inwardly from the side wall 12.

A filter medium comprising a pleated filter element 16 reinforced by a perforated cylindrical core 17 is seated in the recess 15.

The element is made of pervious sheet material such as synthetic resin impregnated filter paper, and the core may take the form of a perforated metal cylinder.

The upper end of the filter medium as seen in Figure 4 is seated in an annular recess 18 in a moulded rubber insert 19.

A stack tube 20 is formed as an integral part of the moulded rubber insert and extends almost to the bottom of the central opening in the annular filter medium. A spider 21 is moulded in the mouth of the stack tube at its lower end, for reinforcement. The stack tube serves to prevent oil draining at the central outlet of the filter unit when the filter unit is mounted in an inverted position on the engine block, as is becoming an increasingly common practice with filters of this type. Alternatively the stack tube may be formed as a separate metal or plastics member which is retained in the moulded rubber insert by bonding or by a friction fit. In some embodiments of the invention the stack tube may be omitted.

The moulding 19 has an upwardly extending annular boss 22 with a counterbore 23 which receives a downwardly extending hollow spigot 24 on a reinforcing plate 25 which fits in the top of the canister 11. The engagement of the spigot in the counterbore serves to locate the insert 19 in the radial direction and the engagement of the boss 22 with the underside of the plate 25 serves to locate the insert in an axial direction.

The opening 26 in the plate and spigot is screw-threaded for engagement with a spigot around an oil inlet opening on the engine block.

The reinforcing plate 25 is held in position by spot welding or projection welding to an annular top plate 27 which in turn is secured to the top edge of the cannister 11 bv double seam rolling. The annular top plate 27 is shaped by pressing to form an annular channel 28 which accommodates a sealing ring 29. When the canister is screwed onto the engine block the sealing ring 26 presses against the face of the engine block to form a seal which prevents oil escaping.

In use, oil flows into the canister through apertures 30 in the reinforcing plate 23 and outwardly over the top of the rubber moulding 19. The oil then passes through a nonreturn valve constituted by a resilient annular flap 31 which extends downwardly and outwardly from the rubber insert 19 to engage the side wall of the canister in its normal unstrained position. The flap 21 is moulded integrally with the insert 19. The pressure of the in-flowing oil deflects the flap 31 downwardly and away from the side wall of the canister so that the oil can enter the space between the side wall of the canister and the filter medium. The oil passes through the filter medium and through the perforations of the reinforcing core 17 into the central opening and out of the canister through the stack tube 20 (when fitted), or central outlet hole. When the oil is not circulating the flap 31 engages the side wall 12. Thus if the filter unit is mounted in an inverted position on the engine block the flap 31 serves as an anti-drain valve preventing oil draining from the filter element when the engine is not running.

As alternatives to the arrangement of an anti-drain flap valve shown in the drawing, a flap which extends outwardly only, if the element end has been formed by pre-moulding as will be described below with reference to Figure 5.

To prevent the engine from being starved of oil if the filter medium is blocked, a bypass valve is provided. A series of apertures 32 are formed in the moulded insert 19 extending axially through it and are continued upwards at their upper ends as open channels 33 formed in the sides of the boss 22.

The moulded rubber insert in the region of the lower ends of the apertures 32 provides a seating for an annular washer 34 which fits in the space between the stack tube 20 and the core 17 and constitutes the moving element of the by-pass valve. A spring 35 biases the washer upwardly so as to seal the apertures 32. Under normal conditions when the engine is running the relief valve is closed. However if the filter medium becomes clogged so that the pressure differential between the oil inlet and the oil outlet exceeds a certain predetermined value, the pressure on the inlet side overcomes the pressure of the spring, depressing the annular washer and allowing the oil to bypass the filter medium through the apertures 32.

The filter unit is assembled as follows.

The recess 15 in the end wall of the canister is filled with an adhesive such as plastisol and the filter element 16 and the core 17 are fitted in the recess. The recess 18 in the insert 19 is then filled with plastisol adhesive.

The spring 35 is located in the core 17 and the annular washer 34 is located on the moulded insert. A sealing compound such as "darex" (Registered Trade Mark) is applied to the top plate 27 and the reinforcing plate 25. The rubber insert 19, the reinforcing plate 25 and the top plate 27 are placed on top of the filter element and the top plate is secured to the canister by double seam rolling. The unit is then heated to an elevated temperature over a predetermined time to cure the adhesive and the resin content of the filter medium. The sealing ring is located in the channel 28 and the whole unit is then pressure tested for leaks.

Alternatively the filter element and the core may be assembled together outside the can by casting plastics or other resilient material over the ends to form a separate element which is then loaded into the can with the other elements of the filter assembly.

The filter unit described above differs from conventional canister filter units in several aspects. The conventional practice is to form the filter medium as a separate subassembly comprising a pleated paper element, an inner core, a bottom plate (which sometimes form part of the relief valve mechanism) and an annular top plate which is then inserted into the canister, together with the relief valve mechanism and antidrain valve.

Another feature of the filter unit described above is the formation of the top cap of the filter element, an anti-drain flap valve and the relief valve and possibly also the antidrain stack tube as a single part, preferably moulded in a resilient material such as rubber, or plastics.

In existing designs of canister filter units an anti-drain valve is formed by a flap placed over the inlet openings in the reinforcing plate 23. This however still leaves the problem of oil draining between the surfaces of the top plate and the side wall on the one hand and the reinforcing plate on the other hand. To avoid such leakage it has been necessary in the past to apply a sealing compound between the reinforcing plate and the top plate. By forming an annular flap on a moulded insert at the top of the filter medium, which flap engages the side wall of the canister to form a non-return valve, the above design of the filter unit avoids this problem.

Assembly is simplified by allowing the adhesive - to be heat cured within the can and the design considerably reduces the number of parts and manufacturing operations normally required for the production of similar disposable filter units.

The filter element described above does not have a bottom plate but is seated directly in an annular recess in the end wall of the canister.

Figure 5 shows a modification of the filter unit of Figures 1 to 4. In the embodiment of Figure 5 ends 40 of plastisol are premoulded on the filter element 161 before the filter element is installed in the canister 11l. The moulded rubber insert 191 can then have a simpler construction compared with the embodiment of Figures 1 to 4, with the integrally moulded anti-drain flap valve 311 extending outwardly at the periphery of the moulding to engage the side wall 121. An annular ridge 41 on the underside of the rubber insert 191 serves to form a seal against the top end of the filter element when the filter unit is assembled.

The unit of Figure 5 also has a modified form of washer 341 compared with the washer 34 of the unit of Figures 1 to 4. The washer 341 has a stepped cross-section to provide a rebate on its outer side to accommodate and locate one end of the spring 351 during assembly. The unit of Figure 5 has no stack tube and the spring 351 is much shorter than the spring 35 extending only about one-third the length of the central opening. An annular inwardly projecting shoulder is provided in the central opening by a corrugation 41 in the core of the filter element. The shoulder serves to provide a support for the lower end of the spring 351 and enables the same size of spring to be used with different sizes of filter element.

WHAT WE CLAIM IS:- 1. An oil filter unit comprising a canister with bottom and side walls, a top plate, an annular filter element in the canister, one end of the filter element abutting the bottom wall of the canister, a moulding which is fitted over the end of the filter element remote from the bottom wall and has at its periphery an antidrain flap valve which engages the side wall of the canister and a pressure relief by-pass valve, the moulding, anti-drain flap valve and the seat of the pressure relief by-pass valve being formed as a single part.

2. An oil filter unit according to claim 1 in which a stack tube extends into the central opening in the filter element from the end remote from the bottom wall, the stack tube, the moulding, the anti-drain flap valve and the seat of the pressure relief by-pass valve being formed as a single part.

3. A filter unit according to claim 1 in which the stack tube is formed as a separate piece secured to the single part comprising the moulding, anti-drain flap valve and the seat of the pressure relief valve.

4. An oil filter according to claim 1, 2 or 3 in which the said single part is moulded of a flexible resilient material.

5. An oil filter unit according to claim 4 in which the flexible resilient material is rubber or plastics.

6. A filter unit according to any of claims 1 to 5 in which the flap valve projects downwardly and outwardly at the outer edge of the said moulding to engage the side wall of the canister.

7. A filter unit according to any of claims 1 to 6 in which the bottom wall of the canister has an annular recess which receives the said one end of the filter element.

8. A filter unit according to claim 7 in which the element is secured in the process with an adhesive which is heat cured within the canister.

9. A filter unit substantially as described hereinbefore with reference to the accompanying drawings.

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

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. and the design considerably reduces the number of parts and manufacturing operations normally required for the production of similar disposable filter units. The filter element described above does not have a bottom plate but is seated directly in an annular recess in the end wall of the canister. Figure 5 shows a modification of the filter unit of Figures 1 to 4. In the embodiment of Figure 5 ends 40 of plastisol are premoulded on the filter element 161 before the filter element is installed in the canister 11l. The moulded rubber insert 191 can then have a simpler construction compared with the embodiment of Figures 1 to 4, with the integrally moulded anti-drain flap valve 311 extending outwardly at the periphery of the moulding to engage the side wall 121. An annular ridge 41 on the underside of the rubber insert 191 serves to form a seal against the top end of the filter element when the filter unit is assembled. The unit of Figure 5 also has a modified form of washer 341 compared with the washer 34 of the unit of Figures 1 to 4. The washer 341 has a stepped cross-section to provide a rebate on its outer side to accommodate and locate one end of the spring 351 during assembly. The unit of Figure 5 has no stack tube and the spring 351 is much shorter than the spring 35 extending only about one-third the length of the central opening. An annular inwardly projecting shoulder is provided in the central opening by a corrugation 41 in the core of the filter element. The shoulder serves to provide a support for the lower end of the spring 351 and enables the same size of spring to be used with different sizes of filter element. WHAT WE CLAIM IS:-

1. An oil filter unit comprising a canister with bottom and side walls, a top plate, an annular filter element in the canister, one end of the filter element abutting the bottom wall of the canister, a moulding which is fitted over the end of the filter element remote from the bottom wall and has at its periphery an antidrain flap valve which engages the side wall of the canister and a pressure relief by-pass valve, the moulding, anti-drain flap valve and the seat of the pressure relief by-pass valve being formed as a single part.

2. An oil filter unit according to claim 1 in which a stack tube extends into the central opening in the filter element from the end remote from the bottom wall, the stack tube, the moulding, the anti-drain flap valve and the seat of the pressure relief by-pass valve being formed as a single part.

3. A filter unit according to claim 1 in which the stack tube is formed as a separate piece secured to the single part comprising the moulding, anti-drain flap valve and the seat of the pressure relief valve.

4. An oil filter according to claim 1, 2 or 3 in which the said single part is moulded of a flexible resilient material.

5. An oil filter unit according to claim 4 in which the flexible resilient material is rubber or plastics.

6. A filter unit according to any of claims 1 to 5 in which the flap valve projects downwardly and outwardly at the outer edge of the said moulding to engage the side wall of the canister.

7. A filter unit according to any of claims 1 to 6 in which the bottom wall of the canister has an annular recess which receives the said one end of the filter element.

8. A filter unit according to claim 7 in which the element is secured in the process with an adhesive which is heat cured within the canister.

9. A filter unit substantially as described hereinbefore with reference to the accompanying drawings.