JPH0239926B2 - - Google Patents

Description

Claim 1: A filter for separating solid particles from gaseous or liquid media, in particular dust particles from atmospheric air, consisting of a permeable, shape-stable, porous shaped body, the filter comprising a permeable, shape-stable, porous shaped body; Large pores on the surface are filled with a filling material of defined particle size, in which case a range of air permeability with different but definable pore diameters depending on the particle distribution of the filling material. in which the filler material 5 is elastic and consists of polytetrafluoroethylene and has an extremely smooth, non-wettable surface (25-57) with high sliding properties; The filler material 5 is fixedly connected to the molded body via an adhesion medium, such that alternating deformations of the molded body do not interfere with the fixation of the filler material in the molded body and its fastness. and the molded body consists of thermally bonded particles of granular polyethylene with a content of medium-molecular polyethylene of 20 to 50% by weight and a content of macromolecular polyethylene of 50 to 80% by weight. A filter for separating solid particles from a gaseous or liquid medium, characterized in that:

2. Filter according to claim 1, characterized in that the filter has an elastically inflatable section and a support section (9, 10).

3. The molded body 3 has a larger filter surface than the tongue-shaped walls 28, 29 with a cross section of approximately equal thickness, and for the filtered medium,
2. A filter according to claim 1, having a diamond-shaped or Christmas tree-shaped inner flow cross section.

4 The small pore filling material 5 covers the particles located outside the molded body 3 to a predetermined depth 35, these particles and the spaces between these particles, thereby allowing surface filtration of the medium. 2. The filter according to claim 1, wherein the filter is adapted to be able to

5 The weight ratio of the materials of the molded body 3 and the filling body 5 is approximately
2. The filter of claim 1, wherein the ratio is 100:1.

Description The present invention is a filter for separating solid particles from a gaseous or liquid medium, in particular dust particles from the atmosphere, which comprises a permeable, shape-stable, porous molded body, the surface of the molded body being The large pores in
Filled with filler material of defined particle size,
Depending on the particle distribution of the filler material, air-permeable regions are formed with variable but definable pore sizes.

West German patent application publication specification (DE-
According to OS 2807159), a filter sintered from plastic for atmospheric use is known. This filter is stable in shape and can have an outer filter shape or chamber shape that is compatible with the conditions of use and the corresponding opening cross section of the filter wall.

According to a British patent (GB-PS746380), a similarly shape-stable,
Elastic, porous filters made of plastic are known. This plastic has properties similar to rubber, and the filter itself is constructed in the form of a hose.

Due to their shape, both known filters are designed to be cleaned by backwashing. However, as the years of use increase, the filter resistance gradually increases. The reason for this is that part of the medium to be separated, for example dust, remains attached to the wind blind area of the filter wall or remains embedded in the filter wall during the cleaning process, for example during blowout.

The object of the invention is to create a shape that is easy to produce, can be used for different purposes, can be cleaned without great expense, and that, after cleaning, the filter action can be restored to almost 100% again. The objective is to provide a stable filter.

The object of the invention is to provide a filter of the type mentioned at the outset, in which the filling material is elastic and consists of polytetrafluoroethylene and is very smooth.
It has a non-wettable surface with high sliding properties, the filling material is fixedly connected to the shaped body via an adhesive medium, and the alternating deformation of the shaped body causes the filling material in the shaped body to The fixation and its robustness are not reduced,
The solution is that the molded body consists of granular polyethylene with a medium-molecular polyethylene content of 20 to 50% by weight and a macromolecular polyethylene content of 50 to 80% by weight.

By implementing the invention, the object of the invention is not only achieved in an advantageous manner, but also other advantages are achieved. That is, the pores of the molded body can be reduced compared to known techniques. This reduction can be accomplished in a series of interrelated procedures.

Furthermore, the small pore width on the surface of the sintered body prevents even very fine particles, for example dust particles, from penetrating into the filter. Filtration is thereby carried out on the principle of surface filtration of the filter, in contrast to the known filter felts and filter fleeces. This has the advantage that dry, wet and oily dust particles are separated at the filter surface. Dust particles are completely removed from the filter surface by backwashing or wiping or shaking. The cleaning effect during backwashing is enhanced by the molded body being expanded to some extent by the backwashing flow. The filter surface is elastically stretched or enlarged. This allows the backwash flow to easily dissociate solid particles, especially particles clogging the pores on the filter surface. The formation of cracks in the molded body and in the surface layer is reliably avoided due to the high elasticity of the material and the bonded nature of the material.

Furthermore, due to the very low embrittlement temperature of the particles and compacts forming the surface of the filter, the filter can be used in a temperature range of approximately -70°C to +85°C. This allows the filter according to the invention to be used in air and liquid filtration technology, such as is commonly used in the field of mining technology, air conditioners, combustion engines, oil and water filters.

Mechanical alternating loads due to kneading deformation of the molded body during the filtration and cleaning processes can cause material fatigue when polyethylene is used as the material of the molded body and polytetrafluoroethylene is used as the filler material. does not bring about The aforementioned materials do not swell when exposed to liquids, such as water, since they repel this liquid. Alternatively, polytetrafluoroethylene (PTFE) does not have an adhesive effect on solid particles, thus aiding in thorough cleaning of the filter.

The macromolecular polyethylene component is important with regard to crack-freeness and stability, while the medium molecular polyethylene component ensures an elastic but shape-stable bond between the particles.

If the internal flow cross-section of the medium to be filtered is large and approximately unchanged, relatively high fluid pressure loads or high pressure loads can be achieved by dividing the filter into a deformable section and a section with a supporting effect. guaranteed.

In order to obtain a high filter efficiency and a relatively large filter surface with a small filter weight, the filter element can be constructed in the form of a bellows. Since the bellows-like shape is stable under any loading conditions, every wall section participates in the filtration process. The filter surfaces on the hazardous substance side do not come into contact with each other even under heavy loads.

The drawings show a plurality of embodiments of the present invention, in which FIG. 1 is a side view showing a filter of the present invention, FIG. 2 is a cross-sectional view of the filter in FIG. 4 is a sectional view taken along the line - in FIG. 3, and FIG. 5 is a partial view of the filter in FIG. 2 according to a modified embodiment of the present invention. FIG. 6 is an enlarged view of the surface of the filter, and FIG. 7 is an enlarged view of FIG. 6.

The filter 20 according to the invention essentially consists of a base 21 with fixing holes 22 and a bellows-shaped section 23 .

The section 23 has walls 28, 29, a bottom 30, and sections 8, 9 which are elastic and have a supporting effect or are immovable, as shown in FIGS. 1 and 2.
It consists of a web 10 and a Christmas tree-shaped internal flow cross section 15. The flow cross section 15 consists of channels 16, 17, which open into a main channel 18 on the pedestal side.

The walls 28, 29 and the ribs 24 have a cross section 12 of approximately equal thickness.

According to FIG. 3, particles 1 of polyethylene are bonded together in areas 2 by sintering to form a shaped body 3 with stable shape. As a result, an elastic filter structure is formed that is stable against mechanical loads such as vibration, rocking, pressing load, and shearing.

In the embodiment shown in FIG. 5, differently sized particles 1, 4 of macromolecular and medium-molecular polyethylene are bonded to each other in region 2, for example by sintering.

A filler 5 (FIG. 6) made of polytetrafluoroethylene (PTFE) closes the surface pores of the sintered compact and, in turn, fills the particles 1 and 4 located on the outside.
cover. In this case, the filler 5 is spaced 35 in FIG.
As shown, it extends from the surface of the compact to more than half of the particle surface.

The filler is inseparably bound to the particles 1, 4. A suitable bond can be obtained with commercially available adhesives and/or partial heat treatment.

In Figure 7, sintered polyethylene particles 1 and 4 are 30 to 50 μm or 150 μm in diameter depending on the purpose of use.
The pores 6, which have a size of .about.500 .mu.m, are reduced by a filling material 5 of polytetrafluoroethylene by approximately a factor 10, to pores 7 having a size of about 8 to 10 .mu.m.

In addition to having a rectangular design, the filtering section 23 can also be curved or angular.
This allows the filter elements to be adapted in a simple manner to the given spatial relationships.

The filter element is suitable not only for use in the normal temperature range, but also for air streams containing water, acids and alkalis, for air streams containing oil, and for the separation of solid particles from liquids. Can be done.

To manufacture the filter 20, a molded body with a relatively large pore width is first formed from a coarse material. A large pore width, for example, increases the opening cross section between the sintered particles, but due to the fact that the individual particles are sintered, the shaped body has sufficient stability, especially against mechanical loads. It has the advantage of giving sex. A shape-stable molded body produced in this way, which still has a large open cross-section for the inflow or outflow of the medium to be filtered, leaves the open area of the molded body with a small open cross-section. Post-processed in the form of filling with filler.

(b) A reduction of the aperture cross section of the above type is possible by using a powder consisting of polytetrafluoroethylene with a defined particle distribution as a homogeneous powder or powder mixture. By using the aforementioned powders, the size of the surface pores can be adapted to the medium to be filtered, for example dust. Furthermore, by selecting the filter material, the medium to be filtered can take into account, for example, its dust adhesion and chemical properties.

(b) By configuring the filter as described above,
The filler can be applied to the filter as a suspension of filler and adhesive at a predetermined concentration using, for example, a spray gun, and the distribution of the solids in the sintered filter body can be effected with a brush. In this case, the surface pores are uniformly filled.

(c) Furthermore, if a suspension tailored to the filler is used, the filler can form a porous molded body with a supporting effect, without the adhesive filling the spaces between the pores and impairing the porosity. can be attached onto or to each other.

One possible specification for the particle distribution and thus for the suspension used is: 14 parts by volume of water 12 parts by volume of polytetrafluoroethylene 1 part by volume of adhesive.

The filter 20 of the present invention can be used in automobiles, device motors, and the like.

In the embodiment shown in FIGS. 8 and 9, the filter element 101 is constructed as a hollow body, the filter 101 itself being screwed to an intermediate wall 102 with a sealing effect, except for an opening 106 on the suction side. Closed on all sides. intermediate wall 10
2 has a hole 107 corresponding to the opening 106.

An overpressure accumulator 1010 with a valve pipe 1011, a diaphragm valve 1012 and a solenoid valve 44 for backwashing air flow are arranged in the upper housing 103. A pressure line 1014 of an external compressed air source (not shown) opens into the overpressure accumulator 1010 .

The diaphragm valve 1012 includes a cover 1015 having an opening 1026 and a resilient diaphragm 102.
7 and the valve plate 1 disposed on the diaphragm 1027.
028 and a spring 1029 that tensions the diaphragm 1027.

A flow guide plate 1018 with holes 19 is arranged in the overpressure accumulator 1010 .

The upper casing 103 has a suction connection 1020 for purified air (arrow 1021).

The lower casing 104 is provided with a relatively coarse sheave 1022 on the bottom side. When the filter operates, use the filter tacho tip 105.
Air is sucked in through the bottom opening (sieve 1022). The negative pressure required for this is acting on the suction connection 1020. The solid particles adhere to the surface of filter element 101. The filtered air flows through the inside of the filter element 101 and the opening 10.
6 and through hole 107 to suction connection 1020 .

Overpressure accumulator 1010 and diaphragm valve 1012
An atmospheric overpressure at and gradually builds up during the two cleaning intervals. Cleaning interval is by solenoid valve 1
The diaphragm valve 102 opens the opening 10 through the
It is started by being evacuated via 26. As a result, the overpressure in the overpressure accumulator 1010 instantly causes the valve plate 1028 to separate from the valve pipe 1011.
As a result, a pressure shock (arrow 1013) is generated through the valve pipe 1011, and this pressure shock is transmitted to the hole 1019.
directly acts on the filter element 101 via. The solid particles adhering to the surface of the filter element 101 are blown away from the surface by the air passing through the pores of the filter element 101 and fall through the sheave 1022 of the filter tip 105. The release criterion for solid particles during cleaning is provided by a predetermined amount of negative pressure acting at the suction connection 1020.

In this case, it is advantageous if the air flow at the suction connection 1020 is interrupted in a manner known per se.

In the embodiment shown in FIGS. 10 and 11, filter tacho tip 1030 has substantially the same structure as filter tacho tip 105 shown in FIG.

In this filter tap 1030, the valve pipe 1
031 is closed by a laterally movable valve plate 1032. A compressed compression spring 1033 acts on the valve plate 1032 . This compression spring 1
033 is kept in a tightened state by a locking member 1034 of a solenoid valve 1035. The valve plate 1032 blocks the valve line 1031 from an overpressure line 1036 of an external pressure accumulator (not shown) or from a flow hopper 1037 shown in dash-dot lines.
The valve pipe 1031 is connected to the guide plate 103 arranged like a roof.
It is combined with 8.

Return spring 43 provided for valve plate 1032
The release claw 10 is activated by a double-acting solenoid valve 1040.
41 and a pull-back claw 1042.

When a cleaning interval is required, the solenoid valve 103
5 unlocks the compression spring 1033 and closes the solenoid valve 1.
040 unlocks the release claw 1041. Compression spring 1033 instantly moves valve plate 1032 into the chamber and holds valve plate 1032 there. Thereby, the valve pipe 1031 is connected to the overpressure pipe 1036, and the overpressure of the overpressure accumulator or the damming pressure of the running vehicle acts on the filter element 101 through the valve pipe 1031, and the solid particles are removed from the filter element 101. released from the surface of the filter tip 10
It is carried out from 5.

Filter element 20 and filter element 101 are made of polyethylene and are provided with a filling material made of polytetrafluoroethylene on the surface.

According to FIG. 12, a filter element 1051 having a structure similar to that in FIG. 2 is inserted into a suction connection 1052 or secured by a form-locking connection in a two-part screw-connected filter tap 1050. .

Via the suction connection 1065 contaminated air (arrow 1054) is supplied to the filter element 1051. The filter element 1051 acts over its entire surface, ie on the circumferential surface 1055, the bottom surface 1056 and the top surface 1057. The aforementioned surfaces are bellow-shaped and are designed as surface filtration filters. Cleaning is performed by pressure impact in the direction of arrow 1013.

For cleaning, a special dust container is provided, which can catch solid particles that have fallen from the surface of the filter.