JPH0446605B2 - - Google Patents

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, air filters, etc. of internal combustion engines.

[Technical background of the invention]

The requirements for a filter material used in automobile oil filters and air filters are that it has filtration performance that effectively removes particulates such as dust present in the fluid to be filtered, and that it has good performance over a long period of time. It is especially important to continue to maintain good filtration 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, filter media have been known in which a density gradient is created in the thickness direction of the filter paper by combining filter papers with different fiber densities (for example,
Publication No. 40778).

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 Although it is excellent in that it can achieve a good sieving effect and improve life to some extent by trapping fine particles, 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 (capture) due to mere contact is difficult to occur, and the dust is firmly captured so that it penetrates into the deep layer ( (so-called deep filtration), the filter material is likely to become clogged,
There is a problem that the pressure loss continues to increase.

(b) In conventional filter media, the porosity of the surface of the filter media on the upstream side of the fluid to be filtered is large, so dust is easily incorporated into the surface layer of the filter media, and therefore a dust cake layer is formed 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 (ie, 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 is excellent in both filtration performance and long life.

In order to achieve the above object, the filter medium of the present invention includes:
A filter medium having a density gradient such that the upstream side of the flow of the fluid to be filtered has a low density and the downstream side has a high density in the thickness direction of the filter medium, and the entire surface of the filter medium on the upstream side of the flow of the fluid to be filtered. This is a raised layer formed by raising the fluff in a protruding state over the entire length of the filter, and is strong enough to form a dust cake layer on the tip surface, and also creates unevenness on the surface of the filter material on the downstream side. It is characterized in that high-density parts and low-density parts are formed scattered in the surface direction of the filter medium.

[Embodiments of the invention]

EMBODIMENT OF THE INVENTION Hereinafter, the filter material of this invention will be explained in detail based on the Example shown in an accompanying drawing.

As shown in the cross-sectional conceptual diagram of FIG. 1, the filter medium of the present invention has irregularities on the back side of the base material 1 of the filter medium, and the flow of the fluid to be filtered (in the direction of the arrow in the figure). A raised layer 2 is provided on the surface of the base material on the upstream side, and constitutes a raised layer.

In this way, the filtration material of the present invention has a raised layer formed on the upstream side of the fluid to be filtered, so dust is captured by this raised layer like rime, and a dust cake layer is formed on the raised layer. By utilizing the filtration action (primal filter function) of this cake layer, the filtration performance can be further improved. Therefore, in the filter medium of the present invention, the raised layer has sufficient strength to form the above-described dust cake layer on the tip surface of the raised portion, and also has sufficient strength to form the dust cake layer on the entire surface of the filter medium. It is important that the hair is raised in a wavy and protruding state.

In addition, the said raised layer can normally 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 μm, the length of the fiber protrusion is 80 to 300 μm.
If so, it is sufficient.

Further, in the manufacturing process, a density gradient can be easily formed in the filter material by providing an uneven shape on the surface or back surface of the filter material.

Furthermore, since the filter material of the present invention has irregularities on the back surface, the contact area with metal fittings such as punched metal is reduced, and as a result, the filtration area can be increased, contributing to an improvement in life. do.

Furthermore, the filter medium of the present invention is shown in FIGS. 2 and 3.
As shown in the figure, density gradients are provided in both the thickness direction and surface direction of the filter medium. That is, in the thickness direction of the base material 1, there is a density gradient such that the diameter of the pores 3 gradually decreases from the inlet side to the outlet side of the fluid to be filtered, and also in the surface direction of the filter material. A high-density portion with a small pore diameter and a low-density portion with a large pore diameter are provided in the convex portion and the concave portion, respectively. Therefore, since there is a density gradient in the thickness direction, large-sized particles of dust are first captured in the low-density layer, and smaller-sized particles are sequentially captured toward the downstream side. This makes it possible to exhibit a good sieving effect and increase the amount of dust retained.

Furthermore, since the high-density portions with relatively small pore diameters and the low-density portions with large pore diameters are uniformly distributed in the surface direction of the filter medium, dust capture can progress in stages. I can do it. In other words, clogging due to dust trapping occurs first in the high-density area and then moves to the low-density area, making it possible to prevent a sudden increase in pressure loss compared to when 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, although not shown, in FIG. 2, it is advantageous to provide unevenness on the upstream side of the fluid in order to improve the filtration performance. In other words, in general, large particles accumulate in low-density areas, and small particles tend to be captured in high-density areas. By keeping the level of the dust cake layer constant, it is possible to maintain the flow velocity ratio of the concavo-convex portion constant and improve the filtration performance.

As constituent materials of the filter medium, natural 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.

Methods for providing density distribution in filter media include, for example, combining and integrating filter media with different fiber densities, or supplying papermaking raw material slurries with different properties and fiber distributions in stages during the papermaking process to make paper. methods etc. may be taken.

In addition, as a method for raising the surface of the filter material, for example, by supplying a papermaking raw material slurry flow to one side of the papermaking net and simultaneously sucking it from the other side of the papermaking net, the longitudinal direction of the fibers is directed against the papermaking surface. A raised layer can be effectively formed by vertically oriented.

When the filter material of the present invention is used in an air filter or an oil filter for an internal combustion engine, it is preferable to form the filter material into a cylindrical shape with a chrysanthemum-like cross section in order to expand the filtration area, and furthermore, the end portion is provided with a disc-shaped metal plate. The filter structure is made by joining the two or by integrally molding or gluing a resin plate.

Filtration performance test example Regarding the filter medium A of the present invention and the conventional filter medium B,
Figure 4 shows the results of the filtration performance test described in JIS-D1611.

At this time, the effective filtration area of filtration was 1000 cm ² , the flow rate was 10/min, and the oil temperature was 80°C.

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

〔Effect of the invention〕

Since the filter medium of the present invention has irregularities on the back side of the filter medium, the contact area with metal fittings such as punched metal is reduced, and as a result, the filtration area can be increased, contributing to an improvement in life. do. In addition, since the filter material of the present invention has a specific density gradient in both the surface direction and the thickness direction, it is possible to capture dust in stages, and in this respect, it has a much longer life. can be achieved.

Furthermore, since the filter material of the present invention is provided with a raised layer on the upstream surface of the fluid to be filtered, a dust cake layer is easily formed on the surface of the filter material, and the primal filter effect of this cake layer improves the filtration performance. and improve your life at the same time.

[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... Raised, 3... Pore.

Claims (1)

[Claims] 1 A filter material having a density gradient such that the density is low on the upstream side of the flow of the fluid to be filtered and high density on the downstream side of the flow of the fluid to be filtered in the thickness direction of the filter material, and the surface of the filter material on the upstream side of the flow of the fluid to be filtered is This is a raised layer that is raised in a raised state over the entire surface, and has sufficient strength to form a dust cake layer on the tip surface, and also has a raised layer on the surface of the filter material on the downstream side. A filtration material characterized by providing unevenness and further having high-density parts and low-density parts scattered in the surface direction of the filtration material.