WO1997033677A1

WO1997033677A1 - Filtering medium in sheet form for filters of fluids in general, particularly for oil filters for internal-combustion engines

Info

Publication number: WO1997033677A1
Application number: PCT/EP1997/001152
Authority: WO
Inventors: Alberto Fracassi
Original assignee: Sogefi Engineering S.P.A.
Priority date: 1996-03-11
Filing date: 1997-03-07
Publication date: 1997-09-18
Also published as: ITMI960471A3; IT1283227B1; ITMI960471A1; ITMI960471A0; AU2025197A

Abstract

A filtering medium in sheet form (1) for filters of liquids in general and particularly for oil filters for internal-combustion engines, comprising, on its surface, regions (2, 3, 4, 5, 6) having a differentiated filtration degree.

Description

FILTERING MEDIUM IN SHEET FORM FOR FILTERS OF FLUIDS IN GENERAL, PARTICULARLY FOR OIL FILTERS FOR INTERNAL- COMBUSTION ENGINES Technical Field

The present invention relates to a filtering medium in sheet form for filters of fluids in general, particularly for oil filters for internal-combustion engines. Background Art

The lubricating oil of internal-combustion engines, which is continuously pumped from a sump acting as a reservoir during operation in order to lubricate the kinematic couplings of the engines, is conventionally made to pass through one or more filters in order to retain the particles of impurities which might damage the surfaces by making contact therewith.

The problem of filtering a fluid is in any case not exclusively limited to the lubrication circuit of internal- combustion engines, since it also affects, for example, all oleo systems. Conventional filters have various constructive embodiments, all of which, however, substantially consist of a structure for supporting and containing a filtering mass through which the fluid to be filtered is made to pass between a region connected to an inlet coupling and a region connected to an outlet coupling.

The filtering mass, too, assumes the most disparate shapes, both in terms of the material used and in terms of the method for treating it; the filtering medium used most frequently is in any case a sheet of paper which is inserted in the filter after being folded or rolled up according to a wide range of different types in order to give the filtering surface a large area despite being in a compact filter, and two kinds of filtration are very commonly provided, according to requirements, in conventional filters: a so- called coarse filtration, which retains for example particles having a size of more than 25 microns, and a so- called fine filtration, which retains for example particles larger than 7 microns.

The method currently used to provide fine filtration consists in making the entire flow of oil pass through a single filter having two elements with a different degree of filtration: one element provides for coarse filtration and the other one provides for fine filtration, and both elements are hydraulically separated so as to provide two parallel circuits.

Whilst the oil that has been subjected to coarse filtration is sent to the motor, the oil that has undergone fine filtration, which can be quantified as being for example approximately 7% of the total flow, is recirculated n the sump; in this manner, it has been ascertained that within a few minutes all the oil is subjected to fine filtration.

A different embodiment of this method consists in adopting two separate filters having a different filtration degree.

The described method entails some drawbacks, the first one being the fact that since the presence of a circuit for recirculating part of the oil in the sump is required, conventional filters can be installed only on engines having adapted specific provisions, and can be adapted to a limited number of other types w.ith a considerable increase in costs and bulk.

Moreover, the filters are constructively very complicated and therefore scarcely reliable and also cause a heavy ecological burden since they are made of various materials.

DISCLOSURE OF THE INVENTION A principal aim of the present invention is to provide a filtering medium in sheet form for filters of fluids in general, particularly for oil filters for internal- combustion engines, which allows maximum simplification of the filters whereon it is adopted and of the connections of the filters to the engine.

This aim is achieved by a filtering medium in sheet form for filters of fluids in general, particularly for oil filters for internal-combustion engines, characterized in that it comprises regions having a differentiated filtration degree.

The filtering medium is inserted in a filter of the kind currently used for conventional coarse filtration, so that all the oil filtered in the various regions, from the region adapted to provide fine filtration to the region adapted to provide coarse filtration, is conveyed into a single common portion of space, where it mixes and then flows directly towards the engine, no longer requiring the presence of any division inside the filter or of recirculation circuits; all the oil therefore undergoes fine filtration after a few minutes of operation.

BRIEF DESCRIPTION OF THE DRAWINGS Further characteristics and advantages of the invention will become apparent from the following detailed description of a preferred but not exclusive embodiment thereof, illustrated only by way of non-limitative example in the accompanying drawing, wherein the only figure is a view of a portion of a sheet of filtering medium according to the present invention.

WAYS OF CARRYING OUT THE INVENTION With reference to the above figure, the reference numeral 1 generally designates the sheet portion which comprises the regions having a differentiated filtration degree, which are provided in the form of longitudinal strips which alternately have the two different filtration degrees; the regions 2, 3, and 4 provide for a coarse filtration degree whilst the regions 5 and 6 provide for a fine filtration degree. The ratio between the areas of the different regions and the corresponding filtration degrees determines the optimum size of a filter according to the type of motor whereon it must be installed.

The regions having a differentiated filtration degree can assume any configuration apart from the illustrated one constituted by longitudinal strips, for example transverse strips or patches, and can be formed within a single layer through the different constitution of the regions provided during the process for manufacturing said layer, but it can also be obtained by superimposing different layers, rigidly coupled for example by gluing, stitching, welding.

The filtering medium according to the invention can obviously be made of natural or synthetic materials and can be pleated or rolled up in order to form the filtering mass to be inserted in a filter in any manner.

The filtering medium according to the invention therefore offers numerous advantages: it can in fact be inserted in entirely conventional filters, which by now have been extensively tested and found to be reliable, are very simple, and can be installed on any engine since they do not require the presence of recirculation circuits.

These filters also have a minimal environmental impact, both because of their small size and because of their efficiency, which improves the quality of exhaust gases.

It should also be noted that the filtering medium according to the invention is ideally adapted for inclusion not only in lubricating oil filters but obviously also in the filters which are present in all circuits which convey a fluid, whether liquid or gaseous; its efficiency, in the case of filters included in open circuits, such as for example gasoline or Diesel-fuel filters, or air filters of conditioning systems for civil use or for motor vehicle cabins, resides in the fact that the fluid circulating in these circuits undergoes better filtration than offered by filters provided with conventional filtering masses.

The described invention is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept.

Claims

1. A filtering medium in sheet form for filters of fluids in general, particularly for oil filters for internal-combustion engines, characterized in that it comprises regions having a differentiated filtration degree.

2. A filtering medium according to claim 1, characterized in that it comprises regions having a differentiated filtration degree with a variable area ratio and filtration degree.

3. A filtering medium according to claim 1, characterized in that it comprises two kinds of variously distributed regions which are adapted to provide fine filtration and coarse filtration respectively.

4. A filtering medium according to claim 1, characterized in that said regions having a differentiated filtration degree are obtained within a single layer through a different constitution of said regions, which is provided during the process for manufacturing said layer.

5. A filtering medium according to claim 1, characterized in that said regions having a differentiated filtration degree comprise a different number of superimposed and rigidly coupled layers.

6. A filtering medium according to claim 5, characterized in that said layers are rigidly coupled by gluing.

7. A filtering medium according to claim 5, characterized in that said layers are rigidly coupled by stitching.

8. A filtering medium according to claim 5, characterized in that said layers are rigidly coupled by welding.

9. A filtering medium according to claim 1, characterized in that said regions having a differentiated filtration degree are provided as strips which alternately have two different filtration degrees.