JPH08930A - Filter material of oil filter for internal combustion engine - Google Patents

Abstract

PURPOSE:To prepare a filter material certainly collecting finely divided carbon sludge and capable of increasing the collection amt. of carbon sludge in an engine oil to a large extent without increasing air passing resistance. CONSTITUTION:Fine cellulose fibers 5 having a fiber diameter 1/10 or less that of cellulose fibers 4 being main fibers are mixed with cellulose fibers 4 and the mixed fibers are formed into a filter material increased in surface area and decreased in filter mesh size by a papermaking method. At least a part of the cellulose fibers 4 or fine cellulose fibers 5 is composed of cationic fibers having positive charge on the surfaces thereof and carbon sludge being an anion is attracted and removed by electrical attraction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter material for an oil filter used for an internal combustion engine such as a diesel engine.

[0002]

2. Description of the Related Art An exhaust gas recirculation system (EGR system) in an engine is being introduced in order to comply with diesel exhaust regulations that are scheduled to be introduced in 1997. This takes some of the exhaust gas from the exhaust system,
Although it is a system that recirculates to the intake system, the EGR rate (E
It is expected that carbon sludge, which is fine particles contained in the lubricating oil, will increase due to an increase in (GR amount / intake air amount) and the like. Further, the improvement of the lubricating oil tends to improve the dispersibility and the carbon sludge in the lubricating oil tends to be made finer. Therefore, improvement of the carbon sludge capturing technology is desired.

[0003] Carbon sludge in lubricating oil is usually trapped by providing an oil filter with a bypass element having a filter size smaller than that of the main filter element and passing the bypass element. Conventionally, cellulose fibers such as pulp fibers have been used as a filter medium, and a bypass element having a filter grain of 2 to 20 μm is constructed by making a fiber having a diameter of 10 to 30 μm, and collision filtration or chemical adsorption is used. Then, the carbon sludge was removed.

However, this system has a limit in the amount of carbon sludge trapped in oil and is not sufficient to cope with the expected increase in carbon sludge. Further, if the filter mesh is made finer in accordance with the miniaturization of carbon sludge, clogging is likely to occur and the life of the element is shortened. Therefore, it is necessary to increase the frequency of element replacement,
Alternatively, there is a concern that the engine may be deteriorated early and the engine may be adversely affected.

By the way, carbon sludge is usually negatively charged, and it is considered that the carbon sludge is electrically adsorbed and captured. An electret filter medium is known as a filter medium utilizing an electric adsorption action.
Japanese Patent No. 23649 discloses that an electret whose polarization direction is forcibly aligned by applying a strong electric field while heating is used as a filter material. On the surface of the electret filter medium, positive charges and negative charges appear separately, and it is possible to adsorb and remove the charged particles by the electric action.

[0006]

However, the electret filter medium is apt to lose its ionization state due to high temperature,
There is a drawback that the surface charge disappears and the filtration performance is lowered, and it is unsuitable as a filter medium for an oil filter used under high temperature conditions. On the other hand, Japanese Patent Publication No. 63-17486 discloses that a filter component is treated with a cation type resin to give a positive zeta potential to the surface of the filter medium. If the surface treatment is performed only with the resin, the particles of the carbon sludge will pass through the openings because of the large filter openings, and the sufficient effect of the surface treatment cannot be obtained. In the above conventional filter,
To compensate for this, fine particles such as diatomaceous earth are added to adjust the porosity and pore size of the filter, but if the filter mesh is reduced by such a method, the porosity of the filter medium decreases,
There has been a problem that the lubrication oil is obstructed and clogging easily occurs.

Therefore, the present invention can sufficiently capture even finer carbon sludge, and the capture efficiency of carbon sludge in oil is increased by increasing the capture amount of carbon sludge in oil without increasing the ventilation resistance. An object of the present invention is to provide a filter material for an oil filter for an internal combustion engine that can be used.

[0008]

Means for Solving the Problems The inventors of the present invention have made earnest studies in view of the above circumstances, and as a result, increase the adsorption area by mixing fine fibers, while imparting a positive charge to the fiber surface. Have found that the trapped amount of carbon sludge in oil having a negative charge can be increased. That is,
The gist of the present invention is obtained by mixing a main fiber constituting a filter medium skeleton and a fine fiber having a fiber diameter of 1/10 or less of the main fiber, and at least a part of the main fiber or the fine fiber is The filter material of an oil filter for an internal combustion engine is characterized in that the surface is a cationic fiber having a positive charge (claim 1).

Cellulose fibers can be preferably used as the main fibers (claim 2). Further, it is preferable to use fibers having a fiber diameter of 10 to 30 μm as the main fibers (claim 7). As the above-mentioned cationic fiber, a fiber whose surface is given a positive charge by coating a cationic resin on the surface of the fiber or substituting a terminal group with a cationic functional group can be used (claim 3). Alternatively, a fiber having a cationic functional group in the composition (claim 4), specifically an acrylic fiber may be used (claim 5). It is desirable that the fine fibers are mixed with the main fibers in a weight ratio of 12: 1 to 4: 1 (claim 6).

[0010]

[Function] Carbon sludge in lubricating oil has a particle size of 0.1 to 1
It is a very small particle of μm, and it is desirable that the filtration pore size is as small as possible in order to increase the physical trapping amount of this carbon sludge. Further, in order to widen the adsorption area, it is desirable to make the fiber surface area as large as possible. In the present invention, the main fibers constituting the skeleton, by mixing fine fibers having a smaller fiber diameter than this, it is possible to greatly increase the fiber surface area per unit volume while maintaining the voids and reduce the filter mesh. It will be possible. Moreover, since the fine fibers that substantially form the filter mesh have a sufficiently smaller fiber diameter than the main fibers, they do not hinder the flow of the lubricating oil and are less likely to be clogged.

Since at least a part of the constituent fibers is a cationic fiber having a positive charge on the surface, the carbon sludge in oil which is an anion is attracted to the surface of the cationic fiber and is electrically adsorbed. It Therefore, even finer carbon sludge that passes through the filter mesh can be reliably captured by electrical adsorption, and due to the combined effect of physical adsorption such as collision with the filter medium, The capturing ability can be significantly improved.

[0012]

EXAMPLES The present invention will be described in detail below with reference to examples. FIG. 1 is an overall sectional view of an oil filter for a diesel engine, and the material of the present invention is used as a filter element for a bypass element. In the figure, in a container 1, a full-flow element 2 and a bypass element 3, which are formed in a cylindrical shape, are vertically arranged. A lubricating oil inlet 11 is formed on the outer peripheral portion of the bottom surface of the container 1, and the lubricating oil passes from the inlet 11 through an inlet passage 12 along the inner peripheral wall of the container 1 to the outer peripheral wall of the full flow element 2. Get inside. A part of the lubricating oil is directly introduced into the bypass element 3. The lubricating oil from which impurities having a relatively large particle size are filtered by the full flow element 2 enters the outlet passage 13 at the center of the container 1 from the inner peripheral wall of the full flow element 2,
It is led out from the outlet 14 at the center of the bottom surface of the container. The lubricating oil that has passed through the bypass element 3 returns to the engine from the bottom surface of the bypass element 3 through the bypass flow passage 15.

The bypass element 3 is installed for the purpose of filtering fine particles such as carbon sludge which cannot be filtered by the full flow element 2. The bypass element 3 is made by mixing a main fiber constituting a skeleton and a fine fiber having a fiber diameter of 1/10 or less of the main fiber, and at least a part of the main fiber or the fine fiber is
The filter material of the present invention is a cationic fiber having a positive charge on its surface.

The main fibers which are the main constituent fibers include linter pulp or wood pulp and the like having a diameter of 10 to 30 μm.
Some cellulose fibers are preferably used. The main fibers are made into paper to form a filter medium. At this time, when fine fibers having a fiber diameter of 1/10 or less thereof are mixed with cellulose fibers, the fibers are not increased in ventilation resistance of the filter medium. The surface area can be increased and the filter pore size can be reduced.

As the fine fibers, cellulose fibers which are the main fibers are finely crushed to 1/10 or less by beating, shearing, tearing, or chemically treating, or, for example, acrylic fibers and the like. A synthetic fiber manufactured to have the above fiber diameter is used. It is also possible to mix both acrylic fibers and cellulose fibers into the main fibers as fine fibers. The smaller the fiber diameter, the larger the amount of mixed paper can be increased and the surface area can be increased. However, since it is not easy to manufacture and the cost is high, it is preferably in the range of 1/10 to 1/300. Good to do. When acrylic fibers are used as the fine fibers, since the acrylic fibers have a cationic cyano group as a functional group, the cationization treatment described later can be omitted.

In the filter medium of the present invention, at least a part of the constituent fibers is a cationic fiber having a positive charge on the surface, which facilitates adsorption and removal of carbon sludge having a negative charge on the surface. You can As the cationic fiber, either a fiber having a cationic property by subjecting the fiber surface to a cationization treatment or a fiber having a positive charge on its surface may be used.

As a method of cationizing the fiber surface,
For example, by applying a cationic resin such as polyamide epichlorohydrin to the fiber surface, a positive charge can be given to the surface. Alternatively, the fiber surface may be cationized by substituting a hydroxyl group, which is a terminal group of cellulose, with a cationic functional group. Specifically, as shown in the following chemical formula, those in which a carboxymethyl group (sodium salt) having a highly cationic sodium atom at the terminal is ether-bonded to the hydroxyl group of cellulose can be mentioned.

[0018]

[Chemical 1]

Then, either or both of the main fiber and the fine fiber are subjected to the cationization treatment to obtain a cationic fiber. Alternatively, only a part of these may be a cationic fiber that has been subjected to a cationization treatment. If a fiber having a positively charged functional group in its structure, such as an acrylic fiber, and the fiber itself has a positively charged surface is used, it is not necessary to perform the above-mentioned cationization treatment.

The mixing amount of the cationic fibers varies depending on the type of lubricating oil and the properties of the carbon sludge in the oil, and is appropriately adjusted to obtain the desired adsorption performance. For example, as the content of fine carbon sludge in oil increases,
It is advisable to increase the proportion of cationic fibers that contribute to electroadsorption.

These main fibers and fine fibers are mixed at a predetermined ratio, and the filter mesh of the filter medium skeleton composed of the main fibers has 2 meshes.
Paper is made so as to have a particle size of ˜20 μm to obtain the filter medium of the present invention.
The mixing amount of the fine fibers varies depending on the fiber diameter, but it is desirable to mix the fine fibers so that the weight ratio of the fine fibers to the main fiber is 12: 1 to 4: 1. Specifically, for example, fine fibers having a diameter of 1/200 of the main fibers are preferably mixed and mixed so that the main fibers and the fine fibers have a weight ratio of about 12: 1 to 4: 1. When the amount of mixed paper is less than the above range, a sufficient effect due to the mixed paper cannot be obtained, and when it exceeds the above range, the filter mesh becomes small and the ventilation resistance increases, which is not preferable.
As the fiber diameter of the fine fibers becomes smaller, the mixed papermaking amount can be increased, and the fiber diameter and the mixed papermaking amount can be adjusted so that the desired fiber surface area and filtration pore size can be obtained.

Next, the filter medium of the present invention was produced as follows. Cellulose fiber as main fiber (fiber diameter 20 μm
) Was processed as fine fibers to have a fiber diameter of 0.1 μm, and then cationized fine cellulose fibers were used. The ratio of both fibers was cellulose fiber: fine cellulose fiber = 12: 1 (weight ratio), and a filter medium was made by mixing and mixing so that the filter mesh of the filter medium skeleton was 2 to 20 μm. The fine structure of the obtained filter material of the present invention is shown in FIG. 2. The surface of the filter mesh composed of the cellulose fibers 4 intersects so that the fine cellulose fibers 5 form a mesh, and is composed of only the cellulose fibers 4. Compared with the conventional filter media, the substantial pore size of the filter mesh is greatly reduced.

Since the fine cellulose fibers 5 have a positive charge on the surface (FIG. 4 (b)), the carbon sludge 6 (FIG. 4 (a)) having a negative charge on the surface passes through the filter medium. , Are electrically adsorbed on the fine cellulose fibers 5 and removed. In this way, since it is an electric adsorption, it is also possible to capture fine carbon sludge,
Moreover, since the fine cellulose fibers 5 constituting the filter mesh are subjected to the cationization treatment, the trapped amount can be greatly improved.

The filter medium of the present invention obtained as described above has a fiber surface area per unit volume increased by about 10 times as compared with the conventional filter medium shown in FIG. 3, while the filter pore size is about 3 minutes. Reduced to 1. As a result, it was possible to capture about twice as much carbon sludge per unit volume as compared with the conventional filter medium.

[0025]

As described above, according to the present invention, by mixing fine fibers, the adsorption area can be greatly increased and the filter mesh can be reduced. Moreover, in the present invention, in addition to physical adsorption such as collision, since the carbon sludge is captured by utilizing the electric adsorption by the cationic fiber,
Fine carbon sludge can also be sufficiently captured, and the amount of capture can be significantly increased. Further, since the filter mesh is made of fine fibers, the ventilation resistance does not increase even if the filter mesh is reduced, and clogging is less likely to occur. Therefore, it is extremely useful as a filter material for an oil filter for an internal combustion engine, and the trapping efficiency can be significantly improved without shortening the life.

[Brief description of drawings]

FIG. 1 is an overall cross-sectional view of an internal combustion engine oil filter using the filter medium of the present invention as a bypass element material.

FIG. 2 is a diagram showing a fine structure of the filter medium of the present invention.

FIG. 3 is a diagram showing a fine structure of a conventional filter medium.

FIG. 4 (a) is a schematic diagram of carbon sludge particles,
FIG. 4B is a schematic diagram showing a trapped state of carbon sludge particles.

[Explanation of symbols]

 1 Container 2 Full Flow Element 3 Bypass Element 4 Cellulose Fiber (Main Fiber) 5 Fine Cellulose Fiber (Fine Fiber) 6 Carbon Sludge Particles

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Masahiro Tomita, 1-1, Showa-cho, Kariya city, Aichi prefecture, Nihon Denso Co., Ltd. (72) Inventor, Yoshihiko Sugiura, 1-1, Showa-cho, Kariya city, Aichi prefecture, Nippon Denso Co., Ltd. Incorporated (72) Inventor Naoya Kato 14 Iwatani, Shimohakaku-cho, Nishio City, Aichi Prefecture Japan Auto Parts Research Institute, Inc.

Claims (7)

[Claims] 1. A main fiber constituting a filter medium skeleton and fine fibers having a fiber diameter of one-tenth or less of the main fiber are mixed and mixed, and at least a part of the main fiber or the fine fiber is surface-coated. A filter material for an oil filter for an internal combustion engine, characterized in that a cationic fiber having a positive charge is used as the material. 2. The filter material for an oil filter for an internal combustion engine according to claim 1, wherein the main fibers are mainly composed of cellulose fibers. 3. The above-mentioned cationic fiber is a fiber whose surface is given a positive charge by coating a cationic resin on the surface of the fiber or by substituting a terminal functional group with a cationic functional group. The filter material for an oil filter for an internal combustion engine according to claim 1 or 2. 4. The filter material for an oil filter for an internal combustion engine according to claim 1, wherein the cationic fiber is a fiber having a cationic functional group in its composition. 5. The filter material for an oil filter for an internal combustion engine according to claim 1, wherein the cationic fiber is an acrylic fiber. 6. The filter material for an oil filter for an internal combustion engine according to claim 1, wherein fine fibers are mixed with the main fibers in a weight ratio of 12: 1 to 4: 1. 7. The main fiber has a fiber diameter of 10 to 30 μm.
7. The filter material for an oil filter for an internal combustion engine according to claim 1, wherein the filter material is a fiber.