JPH0154085B2 - - 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 the 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), there is a problem that the filter medium is easily clogged and the pressure loss increases considerably.

(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, resulting in the formation of a dust cake layer on the surface layer of the filter media. The drawback is that it is difficult. Therefore, a filtration function (that is, a primal filter function) by the cake layer cannot be expected, 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 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 such an object, the filtration material of the present invention is a filtration material having a density gradient in the thickness direction, and has a high density layer provided on the upstream side of the flow of the fluid to be filtered and a high density layer provided on the downstream side of the flow of the fluid to be filtered. The low-density layer is characterized in that the low-density layer has a density gradient such that the upstream side of the flow of the fluid to be filtered is coarse and the downstream side is dense.

[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. A high-density layer 3 is formed on the upstream side of the fluid flow (in the direction of the arrow in the figure), and a low-density layer 1 is formed on the downstream side.

As described above, since the filter material of the present invention has a dense layer on the inlet side of the fluid to be filtered and a coarse layer on the outlet side, relatively large dust particles are not taken into the filter material. It is possible to prevent clogging, and on the contrary, it is highly effective in promoting the formation of a dust cake layer on the surface of the filter medium. Furthermore, since the flow rate when passing through the filter medium tends to gradually slow down, the dust that has passed through the dense layer also tends to adhere to the inside of the filter medium.
Moreover, since the outlet side is roughly configured, there is an effect that the flow resistance due to such dust adhesion does not increase significantly. Therefore, by reducing clogging inside the filter medium and utilizing the filtration action (primal filter function) by the dust cake layer formed on the surface, it is possible to improve the life of the filter medium.

The filter medium shown in FIG. 2 is another embodiment of the present invention, and is an example in which the low-density layer 1 has a denser density gradient. That is, in this example, the size of the pores 2 of the low-density layer 1 has a density gradient such that it gradually becomes smaller in the thickness direction. Therefore, a chamber is formed between the high-density layer 3 and the dense part of the low-density layer 1 (i.e., the downstream part of the fluid), and the action of this chamber prevents pressure loss from increasing and improves life. can be achieved. In other words, the dust particles that have passed through the high-density layer 3 have a reduced flow velocity, and the filtration performance is improved by adhering to the inside of the filter medium through contact and slow sedimentation, and the dust particles also flow inside the chamber space. Since it can move smoothly and relatively freely, it is also advantageous in mitigating an increase in flow resistance. Furthermore, dust that has penetrated into the low-density layer is effectively accumulated within the chamber,
The amount of dust retained by the filter medium can be increased.
This also contributes to longer life.

The filter material shown in FIG. 3 has the following features on the surface of the high density layer 3:
This is an example in which a raised layer made up of raised hair 4 is further formed. In this way, the raised layer formed on the surface on the fluid inlet side traps dust like frost, and a dust cake layer is easily formed on the raised layer, and the filtration effect of this cake layer is utilized. By doing so, the filtration performance can be further improved.

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 microns, it is sufficient that the length of the fiber protrusion is 80 to 300 microns.

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

Moreover, the filter medium of the present invention can be manufactured by combining and integrating a high-density layer and a low-density layer according to a conventional method.

Furthermore, methods for creating a density gradient inside the low-density layer include, for example, combining and integrating filter media with different fiber densities, or using papermaking raw material slurries with different properties and fiber distributions in stages during the papermaking process. A method of supplying paper and making paper may be adopted.

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.

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 the filter material 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〕

The filter medium of the present invention is formed by laminating a high-density layer on the upstream side of the fluid to be filtered and a low-density layer on the downstream side, and furthermore, the low-density layer has a density gradient such that a chamber is formed. Since this is provided, it is possible to promote the formation of a dust cake layer on the surface of the filter medium, reduce clogging inside the filter medium, and effectively prevent a sudden increase in pressure loss. , which is excellent in both improved filtration performance and longer life.

[Brief explanation of drawings]

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...Low density layer, 2...Stomata, 3...High density layer, 4...Fluffing.

Claims (1)

[Claims] 1. A filter material having a density gradient in the thickness direction, in which a high-density layer provided on the upstream side of the flow of the fluid to be filtered and a low-density layer provided on the downstream side are laminated. A filtration material, characterized in that the low density layer has a density gradient such that the upstream side of the flow of the fluid to be filtered is coarse and the downstream side is dense. 2. The filter material according to claim 1, wherein a raised layer is formed on the surface of the high-density layer.