JPS61268322A - Filter material - Google Patents

Abstract

PURPOSE:To extend the life of a filter material, by providing high density parts and low density parts to a filter material in the surface direction in a scattered state and making the density of the filter material low in the upstream side of the flow of a fluid to be filtered and high in the downstream side thereof in the thickness direction of said filter material while forming napped parts on the upstream side surface thereof. CONSTITUTION:Low density parts having voids 2 with a large size and high density parts having small voids are formed to a base material 1 in the surface direction thereof in a scattered state and a density gradient is formed to the base material 1 from the upstream side of the flow of a fluid to be filtered toward the downstream side thereof so as to be changed from 'coarse' to 'dense'. Further, napped parts 3 are formed on the surface of a filter material in the upstream side thereof. By this method, the collection of dust stepwise advances and dust having a smaller particle size is successively collected toward the downstream side by the density gradient in the thickness direction and the formation of a dust cake layer is promoted by napped parts.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a filter material, and particularly to a filter material suitable for oil filters and air filters of internal 111!1 engines.

[Technical background of the invention]

The requirements for a filtration material used in automobile oil filters and air filters are to have filtration performance that effectively removes dust and other particulates present in the fluid to be filtered, and to maintain good filtration over a long period of time. It is especially important to continue to maintain performance.

From this point of view, various filtration media have been proposed in the past, but conventional filtration media are not necessarily fully satisfactory in terms of simultaneously improving filtration performance and prolonging the service life. It's not a thing.

For example, a filter material is known in which a density gradient is provided in the thickness direction of the filter paper by combining filter papers with different fiber densities (for example, Japanese Patent Publication No. 40778/1983).

These density gradient type filter media are formed so that the flow of the fluid to be filtered changes from coarse to dense in the direction from the upstream side to the downstream side, so the low density layer captures large particles and the high density layer A good sieve is excellent in that it is effective and can improve life to some extent by trapping fine particles, but it has the following drawbacks.

(b) In conventional density gradient type filter media, the flow velocity when passing through the filter media is high, and dust adhesion (trapping) due to mere contact is difficult to occur, and the dust is firmly captured so that it sticks to the deep layer ( (So-called deep filtration), there is a problem that the filter medium is easily clogged and the pressure loss increases considerably.

(b) In conventional filter media, since the porosity of the surface of the filter media on the upstream side of the fluid to be filtered is large, dust is easily incorporated into the surface layer of the filter media, resulting in a dust cake layer on the surface layer of the filter media. The disadvantage is that it is difficult to form. therefore,
It is not possible to expect a filtration function (that is, a primal filter function) from the cake layer, and there are major limitations in achieving a long life.

[Summary of the invention]

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a filter material that has excellent filtration performance and has a long life.

In order to achieve such an objective, the filter medium of the present invention has the following features:
High-density areas and low-density areas are scattered in the surface direction of the filter medium, and there is a density gradient such that the upstream side of the flow of the fluid to be filtered is low density and the downstream side is high density in the thickness direction. A raised layer is formed on the surface of the filter material on the flow side of the flow of the filtered fluid.

(Examples of the Invention) Hereinafter, the filter medium of the present invention will be described in detail based on Examples.

As shown in the cross-sectional conceptual diagram of FIG. 1, the filter material of the present invention is
In the planar direction of the base material 1, low-density areas with large diameter pores 2 and high-density areas with small pores 2 are scattered and formed. Also, the flow of the fluid to be filtered (in the direction of the arrow in the figure)
The density gradient is formed so as to change from coarse to dense from the −i1 flow side to the downstream side. Further, a raised layer 3 is formed on the surface of the filter material on the upstream side of the fluid, thereby forming a raised layer.

In this way, the filter material of the present invention has a uniform distribution of high-density parts with relatively small pore diameters and low-density parts with large pore diameters in the plane direction of the base material. The acquisition can proceed in stages. In other words, clogging due to dust capture first occurs in the high-density area and then moves to the low-density area, so it is possible to prevent a sudden increase in pressure loss compared to the case where the density in the planar direction is constant. Further longer life can be achieved. Furthermore, since fine particles are removed more easily in the high-density layer, and large particles are more easily removed in the lower-density layer, filtration performance can be improved by appropriately selecting the density range and area ratio of both layers. It is possible to improve the Further, the density difference in the planar direction may be changed continuously or stepwise.

Furthermore, since the filter material of the present invention has a density gradient in the thickness direction, it captures large-sized dust particles in the low-density layer, and sequentially captures small-sized particles as it goes downstream. It is possible to achieve a good sieving effect and increase the amount of dust retained.

Furthermore, since the filtration material of the present invention has a raised layer formed on the upstream side of the fluid to be filtered, dust is easily captured by this raised layer like rime, and a dust cake layer is easily formed on the raised layer. Therefore, by utilizing the filtration action (primal filter function) of this dust cake layer, the filtration performance can be further improved.

In addition, the said raised layer can usually be comprised in the state where the edge part of the constituent fiber of a filter medium protrudes from the surface of a filter medium, and is fluffed. The nap from the surface is sufficient to easily collect coarse dust particles and form a dust cake layer, and the density of the nap does not necessarily have to be as dense as that of a lawn. For example, when the size of the dust is about 5 to 70 microns, it is sufficient that the length of the navy blue protrusion is 80 to 300 microns.

FIGS. 2 and 3 are conceptual cross-sectional views of a filter medium according to another embodiment of the present invention, in which a micropox difference is formed by providing unevenness on the surface of the filter medium shown in FIG. This is an example.

In other words, in the filter medium shown in FIG. 2, the surface of the filter medium (fluid inlet side) is provided with unevenness, and the low density area extending from G-J in the surface direction of the base material 1 is formed into a concave portion. The high-density portion is located on the convex portion. On the other hand, in the filter medium shown in FIG. 3, the high-density portion is provided in the recessed portion, and the low-density portion is provided in the convex portion.

In this way, by providing the surface of the filter material with concavities and convexities, the flow resistance also changes between the concave and convex portions, which has the effect of allowing dust to be captured in stages. Furthermore, it is advantageous to improve filtration performance by appropriately changing the flow velocity ratio of the uneven portions. In addition, in general, large particles gather in low-density areas, and small particles tend to be captured in high-density areas, so creating a structure like that shown in Figure 2 is important because it keeps the level of the dust cake layer constant and causes unevenness. It is even more advantageous to maintain a constant flow rate ratio to improve filtration performance.

As constituent materials for the filter medium, natural LLI fibers, synthetic fibers, and mixtures thereof, which are conventionally used as raw materials for filter paper, are used, and additives such as binders and colorants can also be used as necessary.

Examples of methods for providing density distribution in filtration media include a method in which the filtration media responsible for fiber density are combined and integrated;
A method may be adopted in which papermaking raw material slurries having different properties and fiber distributions are supplied in stages during the papermaking process.

When using the filter material of the present invention for an air filter or oil filter of an internal combustion engine, in order to expand the filtration area,
It is preferable to form the filter into a cylindrical shape with a chrysanthemum-shaped cross section, and further to form a filter structure by joining a disk-shaped metal plate to the end, or integrally molding or gluing a resin plate.

Filtration performance test example Regarding filter material A of the present invention and conventional filter material B, JIS-
The results of the filtration performance test described in D1611 are shown in FIG.

At this time, the effective filtration area of the filter material is 1000 cIll
The flow rate is 101/min, and the oil temperature is 80°C.

As is clear from FIG. 4, the filtration I of the present invention can gradually reduce the increase in pressure loss due to the capture of dust in the fluid to be filtered without any change in filtration efficiency, further extending the life of the filter medium. can be improved.

(Effects of the Invention) Since the filter material of the present invention has a specific density gradient in both the thickness direction and the surface direction, the dust sieving effect is effectively exhibited, and the dust capture is visually effective. By making the blockage progress step by step, it is possible to prevent a sudden increase in pressure loss, and the life of the product is improved.

Furthermore, since the filtration device of the present invention has a raised layer formed on its surface, it is possible to simultaneously improve filtration performance and life through the primal filter effect of the dust to turkey layer on the surface of the filtration medium.

[Brief explanation of the drawing]

1 to 3 are conceptual diagrams of cross sections of filter media according to examples of the present invention, and FIG. 4 is a graph showing test results of filtration performance. 1... Base material, 2... Pores, 3... Raised.

Claims (1)

[Claims] 1. High-density parts and low-density parts are scattered in the surface direction of the filter material, and in the thickness direction, the upstream side of the flow of the fluid to be filtered has a low density and the downstream side has a high density. 1. A filter material having a density gradient and a raised layer formed on the surface of the filter material on the upstream side of the flow of a fluid to be filtered. 2. Claim 1, wherein the surface of the filter material on the upstream side of the flow of the fluid to be filtered is provided with irregularities, and the high-density portion or low-density portion in the surface direction is formed in the concave portion or convex portion. Filter media as described.