JPH06142417A - Pleat type filter cartridge - Google Patents

Abstract

PURPOSE:To effectively filter fluid with high accuracy by providing a porous core inserted into nonwoven fabric in the tubular form with a lot of leaves or the outer periphery, continuously tightening and fixing the nonwoven fabric and porous core to form a lot of lateral pleats and forming a fluid circuit on the abutted surface of the leaves and the nonwoven fabric or on the leaves themselves. CONSTITUTION:Nonwoven fabric 3 in the tubular form is formed so as to have a continuous density gradient by a melt blow nonwoven fabric producing method. And a porous core 1 provided with a lot of leaves 2 on the outer periphery is inserted into nonwoven fabric 3 in the tubular form. The nonwoven fabric 3 in the tubular form and the porous core 1 are tightened an fixed by a string 5 to form a lot of lateral pleats. And a fluid circuit 11 is formed on the abutted surface of the leaves 2 and the nonwoven fabric 3 in the tubular form or on the leaves 2 themselves. As a result, a pleat type filter cartridge where even when the particle diameter distribution of particles in the fluid is wide, clogging hardly happen and filtration is effectively performed with high accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pleated filter cartridge which functions particularly efficiently for removing particles in a fluid having a wide particle size distribution.

[0002]

2. Description of the Related Art In general, fluids are often mixed in a wide range from fine foreign particles called ultrafine particles to particles of several tens to several hundreds of microns. Conventionally, as a filter for removing these foreign substances, there are known a volume type filter generally called a depth filter and a pleated type filter in which a filter medium is fold-folded in a vertical direction in order to secure a large surface area and extend the filtration life.

In the former depth filter, in order to efficiently remove foreign matters having a wide area distribution of several tens to several hundreds of microns from fine foreign matters, the inner structure of the cylindrical filter cartridge has a rough outer peripheral portion which serves as a fluid inlet. When the fluid is made to flow, the larger particles are removed at the outer peripheral part of the filter cylinder and the inner peripheral part or the central part is formed. The particles are designed to be removed as they flow to the part. As a result, if the particle distribution and the degree of coarseness and fineness of the filter medium are matched, a predetermined filtration can be performed with excellent economic efficiency.

However, this filter has a small surface area because it is simply cylindrical, and in order to pursue economical efficiency, it is necessary to wrap multiple layers of coarse and fine filter media, which inevitably increases the thickness of the entire filter media. As a result, the filtration resistance increases, and there is a drawback that the number of filter cartridges must be greatly increased in order to secure a predetermined flow rate.

In the pleated filter, a sheet-shaped filter is fold-folded in the vertical direction to secure a surface area and to reduce filtration resistance, so that the drawbacks of the above-mentioned filter cartridge can be solved for the time being. In addition, when the particle size distribution of the particles distributed in the fluid is very wide, even if the surface area of the filter cartridge is secured large, particles larger than the pore size of the filter medium are simultaneously captured on the same surface. Therefore, there is a defect that the filtration life is often shortened as compared with the depth filter.

For this reason, the pleat type filter, which has been widely used in recent years, is constructed by laminating several layers of sheet-shaped non-woven fabric filter materials having different pore diameters to form a pleat filter, and applying the mechanism of the depth filter to the outside. The gradual removal of large particles to small particles from the inside to the inside improves the disadvantages of the pleated filter.

However, even with the improved pleated filter described above, new problems arise when pursuing economic efficiency and extending the filtration life. That is, it is technically and economically limited to superimpose a sheet-shaped non-woven fabric filter material having different pore diameters on a large number of layers, and therefore, it is usually composed of 3 to 4 layers. When trying to selectively trap particles in a fluid having a wide distribution in 3 to 4 layers in each layer,
Except in exceptional cases, inconsistencies between the particle distribution and the pore size of the non-woven fabric occur in any of the layers, causing rapid clogging and often causing trouble.

[0008]

SUMMARY OF THE INVENTION The present invention has been made by paying attention to such a point and makes it difficult to cause clogging even when the particle size distribution of particles in a fluid is wide,
An object of the present invention is to provide a pleated filter cartridge capable of highly accurate and efficient filtration.

[0009]

[Means for Solving the Problems] According to the constitution of the present invention which meets the above object, a tubular non-woven fabric is formed by a melt-blown non-woven fabric manufacturing method so as to have a stepless density gradient, and is incorporated in the tubular non-woven fabric. A large number of leaves are provided on the outer periphery of the porous core, and the tubular non-woven fabric and the porous core are tightened and fixed continuously or at a large number of places to form a large number of lateral folds. The fluid circuit is formed on the contact surface with the non-woven fabric or on the leaf itself. To form a fluid circuit on the contact surface between the leaf and the non-woven fabric, a concavo-convex portion is formed on the front and back surfaces of the leaf, or a net-like object is formed on the contact surface between the leaf and the non-woven fabric. It is only necessary to interpose the one that maintains the fluid circuit. In order to interpose a net-like object or the like on the contact surface, for example, a freely deformable net-like object formed in a cylindrical shape may be covered with the leaf.

To form a fluid circuit in the leaf itself, for example, a hollow leaf is formed from a material having a large number of holes, such as a net-like or lattice-like material, or a net-like or lattice-like material is used. The leaves may be formed on a structure that is three-dimensionally laminated in multiple layers. Needless to say, the leaf thus formed must have such strength that it is not deformed by hydraulic pressure. As a pleat type filter having a lateral fold, a filter for coarse filtration having a lateral fold formed by incorporating a spring has been conventionally known, but since this lateral fold is formed by a spring, It is easily deformed by hydraulic pressure and cannot be used for microfiltration at all.
At present, it is hardly used industrially even for coarse filtration.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a partially cutaway perspective view showing an embodiment of the present invention, in which a spiral leaf 2 is provided on the outer periphery of a porous core 1.
Is provided, and the outer periphery of the leaf 2 is covered with a tubular non-woven fabric 3 having a stepless density gradient, and end plates 4, 4'are fitted to the upper and lower ends, It is constituted by tightening a string 5 along the spiral of the leaf 2, forming spiral lateral folds on the outer periphery, and forming concavo-convex portions that form a fluid circuit on the front and back surfaces of the leaf.

Next, a method for manufacturing the pleated filter of the present invention constructed as described above will be described. FIG. 2 is a schematic view of molding a tubular nonwoven fabric used in the present invention,
The molten resin 6 extruded from the extruder into the nozzle is atomized together with the compressed air from the nozzles 7a, 7b, 7c and is sprayed onto the rotating mandrel 8 below the nozzle. In the above embodiment, the mandrel 8 is rotated at about 2500 RPM and the sprayed resin is continuously coated on the outer circumference. At the same time, the coating material is delivered by the delivery rolls 9 and 9 ′ and cut into a predetermined length by the cutting blade 10 to obtain the tubular nonwoven fabric 3.

In the above embodiment, the condition of the delivery roll was set so that the outer diameter of the tubular nonwoven fabric 3 was 64 mm, and the tubular nonwoven fabric 3 was cut with a cutting blade so that the total length was 620 mm. In the above embodiments, polypropylene resin is used as the molten resin 6, but other raw materials such as polyester, nylon, Teflon, etc. may be used as long as the nonwoven fabric can be formed by the melt blow method. May be and is not particularly limited. In the above embodiment, the first group nozzle 7a discharges fibers having an average diameter of 5μ and the second group nozzle 7b discharges 10μ.
The nozzle diameter and other conditions were set so that the fibers having the average diameter were discharged and the fibers having the average diameter of 15 μm were discharged from the third group nozzle 7c. In the present invention, it is needless to say that the type and number of nozzles, the fiber diameter to be discharged, etc. may be appropriately selected according to the intended filter, and are not particularly limited.

As shown in FIG. 2, the injection states of the nozzles of the first group to the third group are such that the injection from the first group nozzle 7a and the injection from the second group nozzle 7b overlap and the second group nozzle The conditions are set so that the injection from 7b and the injection from the third group nozzle 7c overlap. As a result,
As shown in FIG. 3, the internal structure of the tubular non-woven fabric has no density step, that is, an analog density gradient.

Next, as shown in FIG. 1, a polypropylene spiral leaf 2 having a spiral pitch of 14 m formed by injection molding is fitted on the outer periphery of the polypropylene porous core 1, and the spiral leaf 2 is inserted.
An outer diameter of 64 mm, an inner diameter of 58 mm obtained as described above,
The tubular nonwoven fabric 3 having a total length of 620 mm was covered. Then, a tubular non-woven fabric 3 is attached to the porous core 1 along a spiral with a string 5 of polypropylene strong twisted yarn having a diameter of 1.5 mm.
1 to form a cartridge cartridge intermediate body having a total length of 250 mm, and finally end plates 4 and 4'were welded to both ends to form the cartridge filter of the present invention shown in FIG.

The surface area of the lateral pleated filter thus obtained was about 0.11 m ² , and it was possible to secure the surface area about twice that of the conventional cylindrical filter. As shown in FIG. 1, since the tubular non-woven fabric (filter material) 3 is tightly bound by the string 5 along the spiral leaf 2, the filter material 3 does not move due to the pulsation of the fluid.
A reliable filtration accuracy can be obtained. Since the corrugated unevenness 11 directed toward the center is formed on the leaf 2, even if the filter medium is stuck to the leaf 2 due to the pressure of the fluid, the unevenness 11 forms a fluid circuit, so that the flow of the fluid is not hindered.

In the above embodiment, the leaf 2 is formed in a spiral shape, but any kind of material may be used as long as it can form a lateral fold in which the filter medium does not move due to the pulsation of the fluid, such as a horizontal donut shape. Other shapes may be used. The leaves 2 may of course be formed integrally with the porous core 1. In the above embodiment, the filter medium 3 is bound by the string 5 so as to wrap the spiral leaf 2. However, a molded product other than the string may be used, and the filter medium 3 is moved by the pulsation of the fluid. There is no particular limitation as long as it can be fixed so as not to exist. The materials for the porous core 1, the leaf 2, the cord 5, the end plates 4, 4 ', etc. used in the present invention are not particularly limited as long as they are the materials usually used for this kind of purpose.

Next, using a pleated filter cartridge (Sample A) having a surface area of 0.11 m ² manufactured as described in the above example and a conventional nonwoven fabric shown in FIG. A pleated filter cartridge (Sample B) formed to have a surface area of 0.11 m ² was subjected to a filtration life comparison test using a filtration tester. In the conventional non-woven fabric shown in FIG. 4, the surface has a fiber diameter of 15 μm on average, the intermediate layer has a fiber diameter of 10 μm on average, and the back surface has a fiber diameter of 5 μm on average.

The test uses JIS 8 test powders,
Water was used as the fluid, the test powder was added at 10 g / hour, and the differential pressure when measured at a flow rate of 15 l / min was measured. Results are shown in FIG. As is clear from FIG. 5, when the conventional pleated filter cartridge (A in the figure) was used, the time required to reach a differential pressure of 1 kg / cm ² was 3.7 hours, whereas the pleated type cartridge of the present invention was used. The filter cartridge (B in the figure) has a differential pressure of 1k.
The time to reach g / cm ² was 5.2 hours.

[0020]

According to the present invention, the following effects can be obtained. (1) An analog density gradient of a filtering material according to an analog distribution of particle diameters is formed by forming a one-layer non-woven fabric from a conventional digital type in an analog manner, that is, in a stepless density gradient. Thus, the filtration life can be extended. (2) By the action of the leaf, the filter medium is constructed so as not to move due to the liquid pressure, so that the filtering accuracy can be improved. (3) Since the leaf forms lateral folds on the filter medium,
A wide filtration area can be secured. (4) Since the fluid circuit is formed on the contact surface between the leaf and the filter medium or on the leaf itself, even if the filter medium is in close contact with the leaf, the fluid circuit maintains a smooth flow of the fluid. (5) The pleated filter cartridge of the present invention is
Functionally, it has the same function as the conventional depth filter, but eliminates the drawbacks of the conventional depth filter, which has a larger surface area and a smaller filtration resistance than the depth filter.

[0021]

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an embodiment of the present invention.

FIG. 2 is a schematic view for explaining a method for manufacturing a tubular nonwoven fabric used in the filter of the present invention.

FIG. 3 is a diagram showing an internal structure of a tubular nonwoven fabric used in the present invention.

FIG. 4 is a diagram showing an internal structure of a conventional non-woven fabric formed of three layers.

FIG. 5 is a diagram showing a comparison test result of filtration life of the filter of the present invention and the conventional filter.

[Explanation of symbols]

 1 Porous Core 2 Spiral Leaf 3 Tubular Nonwoven Fabric 4, 4'End Plate 5 String 11 Concavo-convex Part (Fluid Circuit)

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location D04H 1/42 K 7199-3B

Claims (1)

[Claims] 1. A tubular non-woven fabric formed steplessly by a melt blown non-woven fabric manufacturing method so as to have a density gradient,
A porous core provided with a large number of leaves on the outer periphery, which is installed in the tubular nonwoven fabric, a large number of lateral folds formed by fastening and fixing the tubular nonwoven fabric and the porous core, the leaf and the tubular nonwoven fabric. And a fluid circuit formed on the leaf itself or on the leaf itself.