AU7804394A - Filter device - Google Patents

Description

FILTER DEVICE

This invention relates to a filter device.

The invention relates to a filter device for filtering foreign material from a fluid. Such a filter device can be used as a fuel filter in an automobile.

In many filter devices a paper filter cartridge is used to remove foreign material from fluids such as petrol or diesel oil. The filter cartridges have a finite life because they become clogged and need to be replaced. It is not normally possible to reuse the filter cartridges because they cannot be readily cleaned. Another problem with used filter cartridges is that their disposal causes problems from an environmental point of view because they are usually impregnated with materials which may well constitute serious pollutants. Accordingly special procedures should be observed in disposing of used cartridges.

Thus, paper filter cartridges are relatively expensive because they cannot be reused and also constitute an environmental problem.

The object of the present invention is to provide a new filter device which can be readily cleaned thereby enabling it to be easily reused.

According to the present invention there is provided a filter device for filtering foreign material from a fluid, inlet for fluid which can have foreign material entrained therein, an outlet for the fluid, a filter element for filtering the foreign material from the fluid flowing from the inlet to the outlet, means for defining a chamber into which foreign material not passed through the filter element collects, and means for selectively opening the chamber for removal of the foreign material. Preferably the filter device includes a casing and the filter element is sealed therein.

Preferably the valve means enables foreign material to be removed through the fluid inlet.

Preferably further, the filter device includes a valve seat located adjacent to the inlet and wherein a valve element normally engages the valve seat so as to close the valve. When it is desired to clean the valve, the inlet is disconnected from a fluid inlet line so that the valve can be opened to permit removal of the foreign material.

Preferably further, the device includes biasing means for biasing the valve element into sealing engagement with the valve seat.

The invention also provides a method of moulding a filter device between a moulding cavity and a moulding core comprising the steps of supporting a filter element so that its edges extend into the space between the cavity and core injecting plastics material into said space so as to mould a filter body having the edges of the filter element moulded or embedded therein.

The invention also provides a die for moulding a filter device comprising: a mould cavity and mould core means for moulding a generally hollow cylindrical body therebetween the mould core means including first and second portions which have complementary support surfaces for supporting a web of filter material therebetween during moulding of said hollow cylindrical body.

The invention will now be further described with reference to the accompanying drawings, in which:

Figure 1 is a cross-sectional view through an embodiment of the filter device of the invention;

Figure 2 is a cross-sectional view along the line 2-2; Figure 3 is a cross-sectional view along the line 3-3; Figure 4 is a cross-section through the device showing the valve open for removal of foreign material;

Figure 5 is a schematic longitudinal section through a preferred embodiment of the invention; Figure 6 shows the components of the preferred embodiment prior to assembly;

Figure 7 is a fragmentary view showing a zig-zag filter element;

Figure 8 is a cross-sectional view along the line 8-8;

Figure 9 is a cross-sectional view along the line 9-9;

Figure 10 is a cross-sectional view along the line 10-10; Figure 11 is a side view of an alternative form of the invention;

Figure 12 is a cross-sectional view along the line 12-12;

Figure 13 is a cross-section through a preferred form of injection moulding die used for forming part of the filter of the invention;

Figure 14 shows the die parts separated; Figure 15 is a longitudinal cross-section through a further embodiment of the invention;

Figure 16 is a fragmentary cross-section through part of the embodiment of Figure 15;

Figure 17 shows a plan view of a modified form of filter element; Figure 18 is a side view of the filter element;

Figure 19 is an end view of the filter element;

Figure 20 is an opposite end view of the filter element; and

Figure 21 is a perspective view of the filter element.

The illustrated filter device 2 shown in the drawings is particularly suitable for use as a fuel filter in an automobile but it is to be understood that the device could be used for other purposes. The device 2 comprises a casing 4 comprising a base portion 6 and top portion 8 both of which are preferably injection moulded from plastics material such as nylon. The base portion 6 comprises an open cylindrical portion 10 formed with a frustoconical portion 12. The frustoconical portion 12 is integrally formed with an inlet spigot 14 having an inlet bore 15 therethrough. The lower end of the spigot 14 is formed with a tapered mounting boss 16. In use the inlet spigot 14 is connected to a fluid line (not shown) which is clamped by known means such as a fastening clip or the like.

The top portion 8 comprises a frustoconical body having a lower depending skirt 18 and an integral outlet spigot 20. The outlet spigot 20 is formed with a tapered mounting boss 22 for connecting to a fuel line. A filter element 24 having a downturned peripheral flange 25 is sandwiched at its periphery between the cylindrical portion 10 and the skirt 18 and a shoulder 19 formed internally of the top portion 8. The filter element may comprise a stainless steel or woven nylon mesh having a suitable mesh size for filtering fuel. For instance the mesh may have openings of about 15 microns. Once the filter element 24 is in place, the top portion 8 can be permanently connected to the base portion 6. This can be done by welding or bonding or by a firm friction fit. The filter device is thus a sealed filter device, i.e. a filter device in which the casing cannot be opened to give access to the filter element.

The device 2 includes a valve 26 formed by means of a valve seat 28 and valve element 30. In the illustrated arrangement, the valve seat 28 comprises part of the inner surface of the frustoconical portion 12. The valve element 30 comprises a conical lower wall formed on a cup shaped body 32. The body 32 is biased downwardly by means of a perforated diaphragm 34 the outer periphery of which is received in a slot formed into the cylindrical portion 10. The perforations 48 in the diaphragm 34 are relatively large, that is to say, of the order of 1 to 2mm in diameter. The bottom 36 of the body 32 is formed with an actuating shaft 38 which is preferably of cruciform cross-section, as shown in Figure 3. The bottom 36 includes four ducts 40 which form fluid communication passages from the passages 42 between the arms of the cruciform shaft 38 to the interior of the body 32, as best seen in Figure 2.

When the device 2 is used in the fuel line of an automobile, fuel passes through the inlet spigot 14 in the passages 42 between the arms of the cruciform shaft 38. The passages 42 connect with the ducts 40 so that the fluid then flows into the body 32 and then into an inlet chamber 44 located within the cylindrical body 10 and above the diaphragm 34. The fuel then flows through the filter element 24 into an outlet chamber 46 located within the top portion 8 and above the filter element 24. The fuel then flows through the outlet spigot 20 to the engine. Any foreign material such as solid particles or water droplets (which are larger than the mesh size of the filter element 24) will not pass through the filter element 24 and will fall onto the perforated diaphragm 34. Particles can then pass through the perforations 48 in the diaphragm 34 and collect in a collecting chamber 50 which is defined between the inside wall of the frustoconical portion 12, the outer wall of the body 32 and the lower surface of the diaphragm 34. The valve 26 can then be activated in order to remove the foreign material which has collected in the collecting chamber 50.

In the illustrated arrangement the valve 26 is operated by first removing the inlet line (not shown) from the inlet spigot 14 so as to expose the end of the shaft 38 which projects from the end of the inlet spigot 14. The end of the shaft 38 is pressed so as to unseat the valve element 30 from the valve seat 28. As best seen in Figure 4, this creates a gap 52 between the valve seat 28 and element 30 so that the foreign material can then pass through this gap into the passages 42 and so be discharged through the inlet spigot 14.

In the illustrated arrangement, the diaphragm 34 is resilient so that it is flexed upwardly as shown in Figure 4 during the opening movement of the valve. The diaphragm 34 provides the downward resilient force to normally keep the valve closed, that is to say with the valve element 30 sealingly engaged with the valve seat 28.

It is preferred that at least the base portion 6 of the casing is formed from transparent plastics materials (which are chemically inert to fuels) are used so as to provide for easy inspection of the inlet chamber 44 and collecting chamber 50. In the illustrated arrangement, the diaphragm 34 is shown as being integrally formed with the body 32 but it will be appreciated that it could be a separate element connected to the body. Alternatively, the diaphragm 34 could be integrally formed with the base portion 6. In alternative arrangements, a compression spring or the like could be used to bias the valve closed.

It is normally preferred to arrange for the device 2 to be operated in a position wherein the filter element 24 is horizontal but this is not essential. For instance, if the device were used in a position in which the filter element 24 were vertical, the foreign material would collect within the lower part of the inlet chamber 44. When it was desired to clean the device the inlet line could be removed and the device would then be rotated so that the inlet spigot 14 is directed downwardly. The foreign material would then pass through the perforated diaphragm 34 into the chamber 50 from where it can be expelled by opening the valve 26 as before.

In a modified arrangement, it would be possible to omit the valve 36. In this case it would be desirable to use the valve 2 in the horizontal position, that is to say with the inlet and outlet spigots 14 and 20 generally horizontally disposed. In this case foreign material will collect in the lower part of the inlet chamber 44. When it is desired to clean the filter, the fuel line (not shown) connected to the inlet spigot 14 is disconnected and the filter device 2 is then moved to a vertical position so that the foreign material will run out under gravity through the inlet spigot 14. For more positive cleaning, it is preferred to also disconnect the fuel line on the outlet spigot 20 so as to reverse flush the filter. This can for instance be effected by the use of compressed air at a pressure of say 100 psi so as to eject substantially all trapped dirt and water from the filter element 24 and the inlet chamber 44.

Figures 5 to 10 illustrate a modified form of the invention. In these drawings, the same reference numerals have been used to denote parts which correspond to those of the embodiment of Figures 1 to 4. The main difference between the embodiment of Figures 5 to 10 and the previous embodiment is that the filter element 24 has a zig-zag shape so as to increase its surface area and the diaphragm 34 is replaced by resilient arms which are integrally formed with the body 32.

More particularly, the top portion 8 of the casing is formed with a recess 60 which receives one end 62 of the cylindrical portion 10. The other end of the cylindrical portion 10 is itself formed with a flange 63 having an end recess 64. The recess 64 receives a skirt 66 formed on the base portion 6. These components are permanently bonded together by means of ultrasonic welding, adhesives or the like. In this arrangement, the filter element 24 has a generally zig-zag shape so as to increase its effective surface area. The periphery of the filter element 24 is preferably moulded into the sidewall of the cylindrical portion 10 during injection moulding of the latter. This can be accomplished by positioning the filter element 24 in a folded condition in the die so that the peripheral edges of the filter element extend into the moulding cavity used to form the cylindrical portion 10. The core of the moulding die can conveniently be formed with two complementary surfaces which correspond to the position of the filter element 24 so as to hold the filter element 24 in place during the moulding process. On separation of the mould halves the complementary core elements separate so that the filter element 24 is moulded in its correct position within the body 10.

In order to decrease the likelihood of imperfect bonding between the periphery of the filter element 24 and the cylindrical portion 10, the body 10 is moulded with zig-zag mounting portions 68 and 70 which receive the peripheral edges 72 of the filter element 24, as best seen in Figures 7 and 8. Where the material used to form the body 10 is the same as that used to form the filter 24, the peripheral edges 72 will normally be melted into the body 10 and therefore lose their separate identity.

In this embodiment, the valve element 30 is formed as a part conical surface on the end of the body 32. The inner end of the body 32 is integrally formed with four resilient arms 74 which are also integrally formed with a mounting flange 76, as best seen in Figure 9. The flange 76 is sandwiched between the end of the body 10 and the adjacent part of the base portion 6, as best seen in Figure 5. The actuating shaft 38 extends through the inlet spigot 14 so that it can be used to unseat the valve element 30 from the valve seat 28, as in the previous arrangement. In the illustrated arrangement, the actuating shaft 38 has a three sided configuration, as seen in Figure 10. This arrangement functions generally in the same manner as that of the previous embodiment, the resilient arms 74 serving to bias the valve element 30 into sealing engagement with the valve seat 28. The arrangement has, however, the advantage of a substantially increased surface area for the filter element 24 therefore generally increasing the capacity of the filter and decreasing the frequency of cleaning required for the filter. Figure 6 shows the various components prior to assembly. In this drawing, the body 32 is separate from the arms 74 but clearly they can be integrally formed.

In an alternative arrangement, it would be possible to integrally mould the cylindrical portion 10 and the base portion 6. In this case the filter element 24 would be held in the mould, as described previously, together with the body 32 and actuating shaft 38.

Figures 11 and 12 illustrate a slightly different configuration for the body 32 and actuating shaft 38. In this arrangement the flange 76 is moulded with an annular skirt 80 which in use is seated against the inner face of the cylindrical portion 10. The actuating shaft 38 is of circular cross-section and is supported by webs 82 within the hollow body 32 so as to define the ducts 40 which permit fuel to pass through the inlet spigot 14 into the inlet chamber 44. When the filter is to be cleaned, the inlet fuel line is disconnected from the inlet spigot 14 and the shaft 38 is pressed so as to disengage the valve element 30 from the valve seat 28, as described previously.

Figures 13 and 14 diagrammatically illustrate a preferred form of die for forming the cylindrical portion 10 in accordance with the invention. The die 100 comprises a stationary half 102 which in use is mounted on a mounting plate of an injection moulding machine (not shown). The die includes a movable half 104 which in use is mounted to the movable plate (not shown) of an injection moulding machine. The movable half 104 includes a cylindrical moulding cavity 106 formed with a rebate 108, these parts in use forming the cylindrical sidewall of the portion 10 and the flange 63. The mould half 102 includes a first core element 110 and the mould half 104 includes a second core element 112. As best seen in Figure 13, the mould elements have complementary support surfaces 114 and 116 which in use hold a web 118 of the filter material between them in the zig-zag configuration during the moulding process. Accordingly there is preferably a slight clearance between the complementary surfaces 114 and 116 so that the web 118 can be accommodated snugly therebetween. The outer cylindrical surfaces 120 and 122 of the core members 110 and 112 form the core of the moulding cavity which defines the cylindrical internal bore of the portion 10. The cylindrical surfaces 120 and 122 are also formed with rebates which in use form the mounting portions 68 and 70. The rebates have been omitted from Figures 13 and 14 for clarity of illustration. The mould half 102 includes a rib 124 adjacent to the surface 120 so as to form the recess 64 in the flange 63.

As illustrated in Figure 14, the core element 110 includes a slidable central portion 126 which is resiliently biased by means of a compression spring 128 towards the other core element. The other core element 112 is also slightly mounted in the mould half 104 and is resiliently biased towards the element 110 by means of a compression spring 130. The arrangement is such that when the mould halves 102 and 104 are separated, the central portion 126 and the core element 112 are biased to the position as shown in Figure 14. In this condition a web 118 is introduced between the surfaces 114 and 116. When the mould is closed, the leading finger 132 of the central portion 126 of the core element pushes the web of filter material into the central trough 134 of the surface 116. As closing movement of the mould halves continues, the other parts of the surfaces 114 and 116 will cause the filter material to be correctly disposed between these surfaces without tearing. The peripheral margins of the web 118 will lie in the space between the cavity 106 and the core elements 110 and 112. When the die is closed the molten plastics material is introduced into the mould cavity and it substantially melts all of the peripheral portions of the web in the mould cavity so that the zig-zag form of filter element 24 is integrally moulded with the body 10. An ejection sleeve may be provided to surround the core element 112 to remove the moulded body 10 from the core in accordance with known techniques. The ejection sleeve is not shown in the drawings for clarity of illustration.

It will be appreciated by those skilled in the art that the novel moulding method and injection moulding die of the invention is a simple but effective way of producing part of the body of the filter device with the filter element integrally moulded therein.

Figures 15 to 21 diagrammatically illustrate an alternative form of filter device 2 constructed in accordance with the invention and the same reference numerals are used to denote parts which correspond to those of the previous embodiments. In this embodiment, the casing 4 comprises first and second components 150 and 152 which are pressed or rolled from sheet metal such as aluminium, steel or the like. The first component 150 is integrally formed with the body portion 10 and outlet spigot 20. The second component 152 is formed with the inlet spigot 14 and frustoconical portion 12. The portion 10 includes a shoulder 154 which terminates with a seam formation 156 which interlocks with a complementary seam formation formed at the end of the frustoconical portion 12. These components are pressed together so as to permanently seal the casing components 150 and 152 together. Located within the casing 4 is a filter- valve assembly 158 which includes a filter element 160 and a valve member 162.

The filter element 160 is moulded analogously to the filter arrangement shown in Figures 7 and 8 (except that the moulded cylindrical wall 10 does not need to be complete, as will be described hereinafter). The filter element includes a ring 164 which is integrally moulded with sidewalls 166, the outer surfaces of which are cylindrical. As seen in Figure 17 however the periphery of the sidewall is zig-zag shaped in order to follow the folded configuration of the filter element 24. The inner faces of the sidewalls 166 are formed with the mounting portions 68 and 70 which receive the peripheral edges 72 of the filter element 74, the arrangement being similar to that illustrated in Figures 7 and 8. In the prefeπed moulding technique of the invention, the filter element 24 comprises woven nylon and the ring 164 and sidewalls 166 are also injection moulded from nylon in a die similar to that shown in Figures 13 and 14. In this case the peripheral edges 72 of the filter element 24 will be melted into the body and lose their separate identity, as in the case of the embodiment of Figures 7 and 8.

The valve member 162 is essentially the same as that shown in Figure 11 except that the mounting flange 76 includes four recesses 168 which receive projecting fingers 170 which are moulded on the ends of the mounting portions 68 and 70 of the filter element 160, as illustrated in Figures 17, 18 and 21. The interlocking recesses 168 and fingers 170 hold the assembly 158 as an integral unit which can be located within the casing components 150 and 152 prior to seaming of the components together. This simplifies assembly. In the preferred assembly arrangement, the ring 164 is seated against the shoulder 154 of the component 150 and is held firmly against the shoulder after joining of the components 150 and 152. This ensures a fluid tight seal between the casing and the filter element 160 so as to ensure that all of the fuel to be filtered passes through the filter element 24. After use the sealed filter device 2 can be removed from the fuel lines and the shaft 38 pressed so as to allow discharge of foreign materials collected in the inlet chamber 44 to thereby clean the device.

In the embodiments of Figures 1 to 14, the wall thickness of the casing is chosen so that it is capable of withstanding an internal pressure of about 50psi. Normally the casing is fully sealed so that the filter can be safely used in fuel lines leading to a carburettor of an internal combustion engine. Where the casing is made from nylon a wall thickness of about 1mm is appropriate. The embodiment disclosed in Figures 15 to 21 has a metal casing and is capable of withstanding higher internal pressures which are developed in fuel lines leading to fuel injectors. In these applications, the casing of the filter device is designed so that it is capable of withstanding pressures up to 120psi to 150psi. The wall thickness will depend on the type of metal used, such as aluminium, stainless steel, powder coated steel or the like but it is envisaged that a wall thickness of about .5mm will give sufficient strength to the casing in order to withstand the operating pressures. Again where the filter device is to be used in fuel lines leading to fuel injectors, that the casing be fully sealed so as to minimise the possibility of leakage.

Many modifications will be apparent to those skilled in the art without departing from the spirit and scope of the invention.

Claims (26)

CLAIMS:

1. A filter device (2) for filtering foreign material from a fluid, inlet (14) for fluid which can have foreign material entrained therein, an outlet (20) for the fluid, a filter element (24) for filtering the foreign material from the fluid flowing from the inlet to the outlet, means (44,50) for defining a chamber into which foreign material not passed through the filter element collects, and means (28,30) for selectively opening the chamber (44) for removal of the foreign material.

2. A device as claimed in claim 1 wherein including a casing (4) and wherein the filter element (24) is sealed therein.

3. A device as claimed in claim 1 or 2 wherein said means for selectively opening the chamber comprises a valve.

4. A device as claimed in claim 3 wherein the valve includes a valve seat (28), a valve element (30) and biasing means (34,74) for biasing the valve element into sealing engagement with the valve seat.

5. A device as claimed in claim 3 or 4 wherein the inlet comprises an inlet spigot (14) having an inlet bore (15), an inner portion of which is within the valve seat.

6. A device as claimed in claim 5 wherein the valve element carried by or formed on a body (32) and an actuating shaft (38) extends through the inlet bore (15), said shaft being operable to move the body (32) against the action of the biasing means (34,74) to unseat the valve element (30) from the seat (32).

7. A device as claimed in claim 6 wherein the shaft is integrally formed with the body 32.

8. A device as claimed in claim 6 or 7 wherein the biasing means (34,74) is integrally formed with the body (32).

9. A device as claimed in any one of claims 6 to 8 wherein an end of the shaft (38) projects from the inlet spigot.

10. A device as claimed in any one of claims 4 to 9 wherein the biasing means comprises a perforated diaphragm (34).

11. A device as claimed in claim 10 wherein a collecting chamber (50) is defined in part between one face of the diaphragm and the valve seat.

12. A device as claimed in any one of claims 4 to 9 wherein the biasing means comprise resilient arms (74) which resiliently bias the body (32) towards the valve seat (28).

13. A device as claimed in any one of claims 1 to 12 wherein the device includes a casing (4) having a cylindrical portion (10) and wherein the filter element (24) extends transversely across the cylindrical portion (10).

14. A device as claimed in any one of claims 1 to 12 wherein the device includes a casing (4) having a cylindrical portion (10) and wherein the filter element is located within the cylindrical portion and disposed so as to have a zig-zag pattern to increase its effective surface area.

15. A device as claimed in claim 14 wherein peripheral edges (72) are moulded integrally into the cylindrical portion (10).

16. A device as claimed in claim 15 wherein base formations (68,70) are formed on an inner wall of the cylindrical portion (10) and the peripheral edges (72) are embedded in said base formations (68,70).

17. A device as claimed in any one of claims 14 to 16 wherein the filter element comprises woven nylon.

18. A device as claimed in any one of claims 13 to 17 wherein the casing includes a frustoconical portion (12) extending between the cylindrical portion (10) and said inlet (14).

19. A method of moulding a filter device (2) between a moulding cavity and a moulding core comprising the steps of supporting a filter element (24) so that its edges (72) extend into the space between the cavity and core injecting plastics material into said space so as to mould a filter body (10) having the edges (72) of the filter element moulded or embedded therein.

20. A method as claimed in claim 19 wherein the filter element comprises woven nylon and said plastics material comprises nylon.

21. A method as claimed in claim 19 or 20 including the step of supporting the filter in a zig-zag configuration generally within the moulding core.

22. A method as claimed in claim 21 wherein the moulding core includes first and second support faces which support the filter in said zig-zag configuration.

23. A die for moulding a filter device comprising: a mould cavity (106) and mould core means (110,112) for moulding a generally hollow cylindrical body (10) therebetween the mould core means including first and second portions (110,112) which have complementary support surfaces (114,116) for supporting a web (118) of filter material therebetween during moulding of said hollow cylindrical body.

24. A die as claimed in claim 23 wherein said second portion (112) is slidable relative to the mould cavity.

25. A die as claimed in claim 24 including biasing means (130) for biasing said one portion (112) out of said mould cavity (106).

26. A die as claimed in claim 24 or 25 wherein a part (126) of the first portion (110) is slidable relative to the remainder thereof and biasing means are provided to bias said part (126) towards said second portion (112).