ARRANGEMENT IN AN OIL FILTER

Abstract: The invention relates to an arrangement in an oil filter (1) for a machine with a centralised lubrication system, for example an internal combustion engine. The filter comprises a cylindrical container enclosing a filter material, the container having a cylindrical wall (1a) and two ends (1b, 1c). Of the latter one end (1b) is adapted for connecting the filter to the centralised lubrication system. The other end (1c) is openable like a cover in order to permit changing of used filter material (2). A seal (7) is provided between the cylindrical wall (1a) and the periphery of the openable end (1c) together with means (1b, 1b2, 6, 1c1) for keeping the openable end fixed under a certain pressure against the seal (7). The seal (7) comprises a circular plate (7b) operatively connected to the openable end (1c), the periphery of the plate supporting a sealing gasket of U-shaped cross section and the apex of the U-shape pointing outwards from the centre of the plate (7b).

Description: Arrangement in an oil filter The present invention relates to an arrangement in an oil filter according to the pre- characterising part of claim 1. The purpose of such an oil filter is to trap particles in the lubricating oil in order thereby to prevent unnecessary wear in the crank bearings of an internal combustion engine, valve timing gear and other moving parts. The filter material is usually paper, which is impregnated with thermosetting plastic so as to maintain its shape and so that it can withstand the pressure differential that occurs when the oil is forced through the filter. In order to obtain a sufficiently large filter surface in a casing which, for reasons of space, must have a relatively small volume, the filter paper is folded. The filter material takes the form of a thick- walled tube with rigid ends. In order that the filter material may be changed without special knowledge or experience on the part of the person who changes the filter material, it is important that when this has been changed it must be easy to achieve complete, reliable sealing between the cylindrical wall and the openable end. W097/18882 relates to a seal for a cylindrical filter chamber with a bottom having an inlet/outlet at one end and a cover at the opposite end. Between a filter element and the wall of the filter chamber there is an annular collecting and distributing space, which is connected to an outlet/inlet. In order to prevent contaminated oil flowing from the inlet/outlet to the outlet/inlet without passing through the filter element, there is a sealing ring, which acts between the bottom of the chamber and the end wall of the filter element. The sealing ring has a U-shaped cross-section with the apex pointing outwards and its legs facing towards the filter element is fixed in a groove in the end of the filter element. The seal absorbs the pressure drop over the filter element; in a contaminated filter this pressure drop may be up to 1.5 bar. The object of the present invention is to produce a seal which fulfils this object without requiring high packing pressures or tightening torque. This object is achieved by means of the characteristic feature set out in the characterising part of claim 1. CONFIRMATION COPY 2 With the seal according to the invention the requisite packing pressure and complete sealing are produced by the oil pressure, even if certain deformations should occur on the openable end as a result of variations in the oil pressure. The invention will now be further explained below with reference to drawings attached in which figure 1 in longitudinal section shows an embodiment of an oil filter with openable end. Figure 2 is a detailed view of figure 1 and figure 3 shows a detailed view of a seal according to the invention without the effect of pressure. In figure 1, 1 generally denotes an oil filter, which comprises a cylindrical container enclosing a filter material 2. The container has a cylindrical wall la and two ends lb, lc, of which the end lb is adapted for connecting the oil filter to the centralised lubrication system of an internal combustion engine, for example, and the end lc can be opened for changing the filter material 2. The end lb has a peripheral seal lbl and a central threaded sleeve lb2. Between the sleeve lb2 and the seal lbl there are inlet openings lb3 for oil that is to be filtered. When the oil filter is fitted to the engine, the sleeve lb2 is joined by means of a threaded connection to an inlet pipe 3 for filtered oil projecting from the engine, and the seal lbl bears tightly against a raised shoulder 4 on the engine block. Oil to be filtered flows through a duct 5, which surrounds the inlet pipe 3 and connects with the engine lubrication points. The oil flow paths through the filter are indicated by arrows 8 and the oil flow to the engine by an arrow 9. The openable end lc has a central threaded sleeve lcl which, with the end in the closed position, is screwed on to one end of a central pipe 6, the other end of which is firmly screwed into the sleeve lb2. The pipe has inlet openings 6a for filtered oil and serves as collecting duct for this. An annular seal 7 is provided for sealing between the openable end lc and a flange lal of the upper edge of the cylindrical wall la. According to the invention the said seal is a seal 7a of U-shaped cross-section supported around the periphery of a circular plate 7b, operatively joined to the openable end 1 c. The said arrangement of the sealing gasket 7a with the lips 7al of the seal 7 pointing 3 towards the centre of the plate 7b means that the said lips tend to be separated by the oil pressure in the filter, so that with increasing pressure one lip is pressed with a certain force against the end lc, and the other against the flange lal . Figure 3 shows the seal 7 fitted on the plate 7b. It will be seen that the lips 7al are somewhat separated; in the fitted state the lips are pressed by the flange lal and by the end lc against the plate 7b, as shown in figure 2. A seal of this type has very low inherent rigidity and without the plate 7b supporting the sealing gasket would be virtually impossible to handle. Due to the fact that the plate is fitted on the sleeve lcl, the seal accompanies the openable end lc when it is fitted or removed. The plate 7b is designed as a spring diaphragm and in addition to holding the seal 7a also has the function of pressing the filter material 2 down and holding this in place in the container. For this purpose an annular groove 7b 1 is provided on the plate 7 which is designed to bear against the upper end of the filter material 2. A pressure equalisation opening 7b2 is provided in the plate 7b in order to ensure equal pressures on both sides of the plate.

Claims: Claims 1. Arrangement in an oil filter (1) for a machine with a centralised lubrication system, for example an internal combustion engine, comprising a cylindrical container enclosing a filter material, the container having a cylindrical wall (la) and two ends (lb, lc), one (lb) of which is designed for connecting the filter to the centralised lubrication system and the other (lc) of which is openable like a cover in order to permit changing of used filter material (2), a seal (7) being provided between the cylindrical wall (la) and the periphery of the openable end (lc) and the seal, viewed in cross-section, having two legs connected to one another and pointing in towards the central axis of the cylindrical container, and means (lb, lb2, 6 lcl) of keeping the openable end fixed under a certain pressure against the seal (7), characterised in that the seal (7) has a low inherent rigidity, for which reason it is supported by the periphery of a circular plate (7b), operatively connected to the openable end (lc), with one leg on each side of the plate. 2. Arrangement according to claim 1, characterised in that the circular plate (7b) is designed to press the filter material (2) by spring force towards the end (lb), adapted for connection of the filter (1) to the centralised lubrication system. 3. Arrangement according to either of the preceding claims, characterised in that the seal (7) has a U-shaped cross-section.

Inventors: HEDMAN ERIK, HEDMAN, ERIK
Applicants: HEDMAN ERIK, PUROLATOR PRODUCTS CO, HEDMAN, ERIK, PUROLATOR PRODUCTS COMPANY
Application year: 1999
Main classification: B01D27
IPC codes: B01D29