FILTER

Abstract: The invention relates to a filter called spin-on filter (1) for filtering a flowing substance, especially to a filter for hydraulic liquid or lubricating oil in combustion motors. The filter (1) comprises a casing (7), open at one end, to be connected to a device assembly (6) including inlet and outlet ducts (4, 5) for the flow to be filtered, and a substantially cylindrical replacable filter means (12) fitted inside the casing, the flow to be filtered having been arranged to pass through the filter means mantle. In accordance with the invention, the cylindrical filter means (12) comprises an end flange (16), designed such that its outer edge (17) simultaneously acts as a seal for the casing (7) end. The flange (16) can be made by injection-moulding plastic in one piece and equipped with flow openings (18) required for the flow to be filtered and communicating with the inlet or outlet ducts in the device assembly. The filter may comprise a joint ring (13), the end flange of the filter means forming a seal (17) between the casing and the joint ring, and a collar (10) with a thread (2), by means of which the assembled filter can be connected as a unit to the device assembly (6) by screwing.

Description: Filter This invention relates to a filter for filtering a flowing substance, such as oil, comprising a casing, which is open at one end and tightly connected to a device assembly including a flow inlet and/or outlet duct, and a substantially cylindrical, replaceable filter means fitted within the casing, the flow, which is steered to the casing from the outside to the inside of the filter means or vice versa, being arranged to pass through the mantle ofthe filter means. One of the applications of encased cylindrical filters is filtering lubricating oil in combustion motors so as to keep the oil free of impurities in operation. A second typical field of application for filters of this type is filtering hydraulic liquid in hydraulic systems. Since the filter is fouled in operation and has to be replaced at intervals, the filter casing must be removable from the device assembly, to which it is attached. There are previously known oil filters, in which the filter means and the surrounding casing have been constructed as a solid unit, replaceable as such. However, such a design is a waste of material and also produces waste in abundance. From an ecological viewpoint, it is preferable to devise a casing that can be opened, so that the clogged filtering means alone is replaced and the casing including a replacement means is put back in position in the device assembly. US patent specification 5 342 519 is cited as an example of such a design, in which the assembled oil filter described comprises a cylindrical, replaceable filter means, a perforated support pipe within the means, a collar as an extension of the pipe, a casing surrounding the means and a joint ring at the casing opening. This filter design includes two threaded joints with O-ring seals, one of which connects the casing to the joint ring and the other connects the assembled filter from the collar to the device assembly so as to provide a sealing between the joint ring and the device assembly. There are also conventional openable filter designs in which one single threaded joint is enough to connect a unit consisting of a filter means, a casing and any joint members to the device assembly. In replaceable filters, the casing must be tightly sealed to the device assembly, since otherwise the medium to be filtered, such as pressurised lubricating oil or hydraulic liquid, will extrude through the joints between the elements into the environment. Such a visible leak will immediately reveal the deficiency or absence of a seal. Ln contrast, current filter designs do not show outwardly whether the filter means is fitted in position or not. With such filters, it is quite possible to remove a clogged filter means and subsequently put the casing back in position, without replacing the removed filter means. Evidently, as a result of such a mistake filtering will no longer take place. The purpose of this invention is to reach a solution in which the risk of misuse mentioned above is eliminated, while providing a more straightforward filter design. The filter in accordance with the invention is characterised by the fact that the cylindrical filter means includes an end flange, whose circumferential outer edge acts as a sealing for the casing end and which has inside this edge one or more flow openings, through which the outside of the filter means mantle communicates with the inlet or outlet duct for flow to be filtered in the device assembly. In a filter in accordance with the invention, the absence of a filter means in the fitted casing also means that the casing is unsealed, which will immediately occur in operation as a leak at the casing joint. In that case, it will be impossible in practical operation to run a motor, a hydraulic system or the like over a longer period of time without filtering. The filter in accordance with the invention has the further advantage of reducing the number of separate components in the design and of providing a less complex assembly, owing to the combined seal for the filter means and the casing end. The filter casing is usually sealed to the device assembly at one end, the assembly comprising both an inlet duct for the flow to be filtered and an outlet duct for the filtered flow, and in that case the casing is closed at its opposite end. The outer edge of the end flange of the filter means then forms an O-seal ring, and the outside of the filter means mantle communicates through the flow opening or openings in this ring with the flow duct in the device assembly. In most cases this flow duct is a inlet duct for the flow to be filtered, the flow being directed from the outside of the cylindrical filter means to its inside, from where the filtered flow continues into an outlet duct in the device assembly; however, an inverse flow direction would be quite as possible in principle. A preferred embodiment of the invention is characterised in that the annular seal formed by the end flange of the filter means bears against the outer surface of the casing opening such that the pressure prevailing within the casing will increase the strain on the seal. This seal position in accordance with the invention, which in fact is independent of the seal design, will provide tighter sealing during the filtering process, unlike many conventional sealing arrangements, including the solution described in US patent specification 5 342 519, in which the seal ring is placed inside the casing end. Besides a casing and a replaceable filter means, the filter design in accordance with the invention preferably comprises a perforated support member with an associated collar within the means, and a joint ring between the casing and the device assembly. In this case, the end flange of the filter means acts as a seal between the casing and the joint ring, and the assembled filter can be connected to the device assembly as a unit by screwing the collar thread into the device assembly. The filter provided with a replaceable filter means in accordance with the invention is particularly suitable as a hydraulic or lubricating oil filter, but is also usable as any liquid filter, such as a water or fuel filter. The invention will be described in greater detail below by means of examples and with reference to the accompanying drawings, of which figure 1 shows an assembled filter in accordance with the invention, and a device assembly to which the filter can be attached by screwing, figure 2 shows the end flange of the filter means pertaining to the filter as cross¬ section II-II of figure 3, figure 3 is a top view of the end flange of the filter means and figure 4 shows the end flange of a filter means of a second embodiment of the invention, as a cross-section corresponding to figure 2. Figure 1 shows a filter in accordance with the invention, called spin-on filter 1, which is particularly suited as a replaceable oil filter in a combustion motor. The filter is composed of elements, which, assembled as in figure 1 , can be connected by a threaded joint 2, 3 to a device assembly 6 comprising inlet and outlet ducts 4,5 for the flow to be filtered. Filter 1 comprises a closed casing 7 preferably made of metal or plastic, which is open at the end facing device assembly 6, a perforated support pipe 9 attached as an extension of a deep-drawn recess 8 at the opposite end of the casing and ending at the end facing the device assembly 6 in a collar 10 provided with an internal thread 2, a cylindrical filter means 12 fitted in the space 1 1 between the casing mantle and the support pipe and with a filtering layer preferably consisting of e.g. fluted paper or non-woven fibre pulp, and a joint ring 13 bearing against the open casing end and having flow openings 14 for the incoming flow of substance to be filtered, which is steered from flow inlet ducts 4 in the device assembly into filtering space 11 within the casing. Joint ring 13 is equipped with an O-ring seal 15, which seals the joint between the joint ring and device assembly 6 when filter 1 is screwed into position. On the other hand, the sealing between the open end of casing 7 and joint ring 13 is provided in accordance with the invention by equipping the cylindrical filter means 12 with an end flange 16, appropriately manufactured by injection moulding plastic, and having an outer edge formed as an O-ring seal 17 between the outer surface of the casing end and the joint ring, and having inside its edge flow inlets 18 for the incoming flow of substance to be filtered, which is directed from the inlet ducts 4 in device assembly 6 into filtering space 1 1 inside the casing. The shape of the end flange 16 of the filter means is shown in detail in figures 2 and 3. The flange comprises a downwardly bent edge portion 17, which acts as an O- ring seal between the outer surface of the casing opening and the joint ring, and flow openings 18, disposed at regular intervals to form a ring inside the edge portion. The bridges 19 between the flow openings 18 will then connect flange 16 of edge portion 17 to the inner portion 20 supporting the end of the filter means. An opening 21 is provided in the centre of flange 16 to enable the flange to be fitted around the filter collar 10 as shown in figure 1. Figure 4 shows an optional embodiment of end flange 16 of the filter means, one of the differences from the embodiment in figures 2 and 3 being that its outer edge 17 acting as a seal has been given a V shape, enabling it to yield by flattening or opening up, depending of the pressure exerted on it. It should be noted in this context that a flexible end flange 16 acting as a seal can be given various designs within the scope of professional know-how. In this case, it is also possible to form at least the components 20 of the flange that bear against the end of the filter means of a more rigid material, alongside which a softer material, particularly suitable as a seal, is used at the outer edge 17 of the flange. A filter 1 assembled as in figure 1 is attached to device assembly 6 by screwing the internal thread 2 in collar 10 into the matching external thread 3 in the device assembly. With filter 1 in operation, the flow to be filtered is directed from inlet ducts 4 through the joint ring and flow inlets 14, 18 in the end flange of the filter means into a filtering space 11 delimited by casing 7, from where the flow is filtered through the filter material layer in filter means 12 and the perforated pipe 9 into the space 22 within the pipe, from where the filtered flow is removed into outlet duct 5 in the device assembly. The flow direction is indicated with arrows in figure 1. The flow direction could be inverse in principle, however, in that case the filter design should be modified such that support pipe 9 would bear against the outer surface of the cylindrical filter means 12. A clogged filter means 12 is replaced by screwing off filter 1 from device assembly 6, by withdrawing casing 7, support pipe 9 and collar 10, formed together as a solid piece, from joint ring 13 and by removing filter means 12 from the space 1 1 between the casing and the support pipe. After this, a new filter means 12 is fitted into space 1 1 with the outer edge 17 of its end flange 16 fitted as a seal around the opening of casing 7, and subsequently joint ring 13 is pressed into position and the filter thus assembled is fixed to device assembly 6 by screwing it to the assembly as a unit. It is obvious to those skilled in the art that the various embodiments of the invention are not restricted to the examples given above, but may vary within the scope of the accompanying claims.Thus, the threaded joint between filter 1 and device body 6 may differ from figure 1 in that the filter collar 10 is provided with an external thread and the device body with a matching internal thread.

Claims: Claims 1. A filter (1) for filtering a flowing substance, such as oil, comprising a casing (7) open at one end, which is tightly connected to a device assembly (6) including a flow inlet and/or outlet duct (4, 5), and a substantially cylindrical, replaceable filter means (12) fitted inside the casing, the flow, which is directed to the casing from the outside (1 1) to the inside (22) of the filter means or vice versa, being arranged to pass through the mantle of the filter means, characterised in that the cylindrical filter means (12) comprises an end flange (16), whose circumferential outer edge ( 17) acts as a seal for the casing (7) end and having inside said edge one or more flow openings (18), through which the outside (1 1 ) of the filter means mantle communicates with the inlet or outlet duct (4) for flow to be filtered in the device assembly (6). 2. A filter as claimed in claim 1, characterised in that the flow opemngs (18) are regularly spaced to form a ring, in which the bridges (19) between the flow openings connect the annular edge portion (17) of flange ( 16) acting as a seal with the inner portion (20) of the flange bearing against the end of the filter means (12). 3. A filter as claimed in claim 1 or 2, characterised in that the flow openings (18) in the flange communicate with the inlet duct (4) for flow to be filtered and that the inside (22) ofthe filter means (12) mantle communicates with the outlet duct (5) for filtered flow in the device assembly (6). 4. A filter as claimed in any of the preceding claims, characterised in that the annular seal (17) is placed against the outer surface of the casing (7) opening such that the pressure prevailing within the casing will increase the strain on the seal. 5. A filter as claimed in any of the preceding claims, characterised in that inside the cylindrical casing (7) an axial support member (9) has been attached such that the replaceable filter means (12) is located in the cylindrical space between the casing and the support member, and that the support member ends with a collar (10) provided with a thread (2) such that the casing, the support member and the collar can be connected as a unit to the device assembly (6) by screwing. 6. A filter as claimed in claim 5, characterised in that the support member consists of a perforated support pipe (9). 7. A filter as claimed in claim 5 or 6, characterised in that the filter comprises a joint ring (13) between the casing (7) and the device assembly (6), the seal (17) provided by the end flange (16) of the filter means ( 12) being located between the casing end and the joint ring. 8. A filter as claimed in any of the preceding claims, characterised in that the end flange (16) of the filter means foirning the seal (17) is manufactured by injection-moulding plastic in one piece. 9. A filter as claimed in any of the preceding claims, characterised in that the filter (1) is a removable hydraulic or lubricating oil filter equipped with a replaceable filter means (12).

Inventors: KANGASNIEMI MARKO, KOIVULA TUOMO, KANGASNIEMI, MARKO, KOIVULA, TUOMO
Applicants: KANGASNIEMI MARKO, KOIVULA TUOMO, PARKER HANNIFINN OY, KANGASNIEMI, MARKO, KOIVULA, TUOMO
Application year: 1996
Main classification: B01D27
IPC codes: B01D27, B01D29, F01M11