RU2134801C1 - Filtering element and method of its manufacture - Google Patents

Abstract

FIELD: mechanical engineering; internal combustion engines; cleaning of exhaust gases and aggressive liquids from admixtures. SUBSTANCE: proposed device can be used in automotive industry in diesel engines as soot filter and in chemical industry as cleaning filter element. EFFECT: increased thermal stability of filtering element, possibility of burning up of soot in element channels. 3 cl, 6 dwg

Description

 The invention relates to a device for cleaning the exhaust gases of internal combustion engines and cleaning aggressive liquids from impurities.

 The invention can be used in the automotive industry in diesel engines as an element of a particulate filter and in the chemical industry as an element of a cleaning filter.

 Known filter element according to German patent N 4117602, F 01 N 3/02 (RZH N 1, 1994) (1), comprising a housing with an outer layer of heat-resistant fibers and a cylinder of microporous ceramics.

 The gases leaving the internal combustion engine enter the housing from the outside, are cleaned through a layer of heat-resistant fibers, and then enter the ceramic cylinder, where they are subjected to final cleaning through the micropores of the cylinder.

 A significant drawback of this filter element is the absence of a branched system of microchannels in the layer of heat-resistant filter fibers, which increases the hydraulic resistance, and insufficient passability of small pores (microchannels) in the ceramic cylinder, which leads to rapid clogging of pores in the ceramic cylinder and a decrease in gas cleaning efficiency.

 Known monolithic ceramic block of a porous structure according to US patent N 4604869, F 01 N 3/02, B 01 D 39/20 (R.J. N 6, 1987) (2), containing longitudinal channels with partitions inside the channels, some extreme whose channels are closed by the front and rear walls.

 The extreme channels are divided into inlet and outlet.

 The inlet channels are open on the front side at the exhaust gas inlet and are closed on the rear side, and the exhaust channels are blocked on the front side of the gas inlet and open on the back side, the middle channels are blocked by partitions.

 Channels form labyrinths (microchannels).

 Gas purification is carried out in the channels by the deposition of soot on the walls of the channels, due to a change in the direction of gas movement, and through the walls of the porous structure.

This block (2) also has significant disadvantages:
- low hydraulic resistance of the channels due to the large cross section of the channels;
- high resistance of the walls of the channels of the porous structure,
- the difficulty of cleaning the porous structure from accumulated soot, which reduces the efficiency of the filter and the quality of gas purification.

 Known catalytic filter for cleaning the exhaust gases of an internal combustion engine according to the author's certificate of the USSR N 1160940, F 01 N 3/28 from 09/30/1980 (3), containing alternately wavy layers of sieve cloth and sheet metal rolled up in a spiral, which form a gas-tight bag.

 The package from the ends has protective covers with inlet and outlet sections.

 The wavy layers of tin form longitudinal channels in which the sieve fabric is located.

 The layers of tin are made of heat-resistant metal.

 The operation of the filter (3) is as follows: the gases enter the end of the filter, pass through a gas-permeable packet of layers of sieve cloth, are cleaned in the channels and exit the other end of the filter.

The disadvantages of the filter (3) include:
- low heat resistance of sieve cloth, metal;
- design complexity;
- one-time use of the filter due to the impossibility of replacing failed elements that have a short service life.

 Known ceramic block filter according to the author's certificate of the USSR N 1752175, B 01 D 25/02, 39/20 from 02/05/1990 and according to US patent N 4464185, B 01 D 39/20, 1984 (4), which is adopted for most essential features as a prototype of the claimed.

 This block is made with longitudinal and transverse honeycomb channels.

 The transverse cellular channels are made inclined to the longitudinal ones and form blind (dead-end) channels when they intersect with the longitudinal ones.

 The operation of the filter is as follows: the liquid or gas entering the channels open at the end of the unit changes the direction of movement and the filtrate is deposited mainly in the dead-end channels.

 The filter is washed after a certain time.

Significant disadvantages of this block (4) are:
- large transverse dimensions of the cellular channels,
- the presence of deadlock channels;
- the difficulty of manufacturing and cleaning channels from filtering elements, which reduces the filter service life.

Common features of the known (4) block and the claimed include:
- solidity of the ceramic block;
- longitudinal and transverse channels in the form of honeycombs.

 A method of manufacturing ceramic elements (1), (2) and (4) includes forming operations by sealing, drying, firing and cleaning the channels after firing.

 A known method of manufacturing a filter element according to the author's certificate of the USSR N 1625320, B 01 D 24/04 of 02/01/1985 (5), including mixing the filter material with a water-soluble binder, the formation of the filter material in the flowing mold in layers, drying, removing from the mold and drawing on one side of a gas-permeable film with microchannels, and on the other a gas-tight film.

 As water-soluble binders, glucose, gelatin, etc. are used.

 As the filter material, fibrous materials are used.

This known method has significant disadvantages:
- low heat resistance of the filter material;
- lack of interconnected microchannels.

 According to most common essential features: mixing the filter material with water-soluble, shaping, drying - the known method (5) is adopted as a prototype.

 The present invention has the goal of eliminating the above (4), (5) disadvantages by changing the design of the cellular channels in the filter element and the method of their manufacture by burning the mesh material during firing.

 A change in the design of the filter element is achieved by the fact that in the monolithic ceramic block, the cellular macrochannels are made in the form of a grid of cells communicating with each other and an embodiment is made in the form of a grid coiled in a spiral with a cylinder with a central hole along the axis of the cylinder.

 The elimination of the disadvantages of the known methods of manufacturing ceramic filter elements is that the shaping of the ceramic material is carried out together with a grid of burnable material, which is burned during firing, then the channels are washed with liquid under pressure.

 When firing, the grid burns out, forming interconnected macrochannels in the form of cells.

Common essential features of the known (4) device and the claimed include:
- monolithic ceramic block;
- longitudinal and transverse macrochannels in the form of honeycombs.

The distinctive features of the proposed filter element from the known (4) include:
- cellular channels in the form of a grid of communicating with each other cells;
- an option made of channels in the form of a grid, helically rolled into a cylinder with a hole along the axis of the cylinder.

In the known device (4), the transverse macrochannels are made at an angle of 45 ^o to the longitudinal channels, are staggered in two mutually perpendicular planes; only a part of the transverse channels is connected to the longitudinal channels; moreover, these channels are not closed to each other in cells.

 In the proposed element, all channels are interconnected in the form of a grid and each cell is also interconnected by channels, regardless of whether the grids from the channels are parallel to each other in a ceramic block or are helically rolled into a cylinder.

 These above distinguishing features are significant, as they allow you to form a grid structure of interconnected channels of different cross-sections, depending on the thickness of the burned mesh; the number of channels in the block increases and the channels themselves in the cross section become transitional between macro- and microchannels, i.e. the body structure of the ceramic block changes: from the ends at the inlet and at the outlet, the channels are open, inside they are penetrated by a mesh structure in the form of cells.

 Based on the above comparative analysis, we can conclude that the new features not known in the above analogues and prototype are significant.

 The positive effect of the new technical solution is that there are no dead ends in the channels, because all channels are interconnected into a network, which ensures a decrease in hydraulic resistance and provides the ability to flush the channels.

The distinctive features of the method of manufacturing the inventive filter element include:
- shaping of the ceramic material in conjunction with a mesh of material that burns out during firing;
- shaping of ceramic material with a grid of layers;
- the formation of channels within the block;
- burning the mesh material during firing;
- washing channels under pressure with liquid after firing.

 These distinctive features, as follows from the above analysis, are not known from information materials.

 On this basis, they can be considered new.

 The above new features are significant, because they help to solve the technical problem - the formation of a system of channels from cells in the form of a grid, with each cell communicating with each other channels; the size of the cross section of the channels and the density of the channels is controlled by the thickness of the mesh material.

 The number of channels is controlled by the number of grids in the cross section of the filter element.

The possibility of implementing the invention is illustrated by drawings, where:
- in FIG. 1 is a general view of a filter element, a longitudinal section;
- in FIG. 2 - cross section aa;
- in FIG. 3 - an embodiment of the device, a longitudinal section;
- in FIG. 4 - scan connection of the longitudinal and transverse channels into the cell;
- in FIG. 5 - place 1 in an increased size;
- in FIG. 6 is an embodiment of a line of a method for manufacturing a filter element.

 The filter element (Fig. 1) consists of: a monolithic ceramic block 1, longitudinal channels 2, transverse channels 3, forming when connecting to each other in the body of block 1, longitudinal cells 4 and transverse cells 5 (Fig. 5), which in turn by means of longitudinal and transverse channels form a grid 6 (Fig. 4).

 At the ends, the filter element has open input sections of 7 channels and output sections of 8 channels in the direction of gas or liquid supply.

 The channels inside the block 1 form a grid 6, rolled into a spiral 9 (Fig. 2) in parallel layers along the axis of the block.

 The shape of the ceramic element can be various: square, rectangular, cylindrical, depending on the shape of the forming mechanism: matrix to the press, nozzle to the extruder, etc.

 An embodiment of the filter element in the form of a cylinder with a central axial hole 10 and an insert plug at the outlet 11 is shown in FIG. 3.

 The filter element is installed in a casing (not specified) having structural devices for receiving, directing and exiting after cleaning gases or liquids.

 The operation of the filter element.

 Waste gases or liquid to be cleaned enter the end of the ceramic block 1 in the inlet sections of the 7 channels, pass along the longitudinal 2, transverse 3 sections of the channels, change the direction of movement, flows meet each other, lose speed and soot or suspended particles of the liquid are deposited on the walls of the channels.

 The purified gas or liquid exits between the casing (not specified) from the outer surface of the element, as well as from the end of the channels 8.

 In the case of the manufacture of ceramic block 1 from porous ceramics or the use of catalytic elements in the ceramic composition that accelerate the cleaning process, the cleaning efficiency of the ceramic element is increased.

 The cleaning in the channels of block 1 is mainly carried out by the rough walls of the channels 2, 3 due to a change in the direction of movement in the cells of the oncoming flows, as well as an increase in the number of small cross-sections of the channels (depending on the thickness of the material and the size of the cells of the burnable mesh).

 A plug 11 is inserted into the filter element (Fig. 3) with an axial cylindrical hole 10.

 Exhaust gases or liquid enter the cylindrical hole 10 from the end, pass through the channel system and exit the outer surface of the unit between the casing (not specified) in its end part at the outlet.

 Preparation method.

 Depending on the mass production, devices of various degrees of mechanization can be used to implement the manufacturing method of the filter element.

In FIG. 6 shows a manufacturing option on a line consisting of:
- conveyor 12;
- feeder 13;
- feed mechanism 14 mesh;
- trickle device 15;
- shaping mechanism 16;
- cutting mechanism 17;
- sealing device 18;
- dried 19;
- furnaces 20.

 A pre-crushed ceramic mixture mixed from an appropriate filter composition is fed by a feeder 13 with a thin layer 21 to the grid 22, which comes from the feed mechanism 14 synchronously to the movement of the conveyor 12.

 In the process of moving on the conveyor 12, the ceramic layer 21 and the mesh 22 are pre-compacted with a load (not specified), then dried on a dressing device 15 to a moisture content of 18-21%, the forming mechanism 16 folds the tape over the edges of the mesh that are free on the side (in the version with an axial hole on roller) into the cylinder and the cutting mechanism 17 cuts off the workpiece 23.

 The blank 23 is fed to a sealing device 18, where in a matrix or nozzle a layer of ceramic with a mesh is compacted, while at the same time giving, if necessary, the desired shape of a cylinder or parallelepiped.

Then, in the dryer 19, the preform is dried at a temperature of 80-95 ^o C and fired in an oven 20 at a temperature of 950-1150 ^o C depending on the composition of the ceramic.

 When firing, the grid 22 burns out, forming a mesh structure of channels in the ceramic block 1.

 After firing (depending on the design of the filter), the ends of the filter element are cut and the channels are washed with liquid under pressure, washing the soot from the burnt mesh.

 During operation, the filter element is also washed under pressure to clean the channels from the filtrate.

 The positive effect of the use of the filter element in the filters for purification of exhaust gases in internal combustion engines consists in the high heat resistance of the element, the possibility of burning soot in the element channels and the cleaning of the channels due to the network of channels communicating with each other.

 The positive effect of using the element in filters for cleaning aggressive liquids is the chemical resistance of the filter element.

Claims (3)

 1. The filter element containing a monolithic ceramic block with cellular channels, characterized in that the cellular channels are made in the form of a grid of communicating with each other cells.  2. The filter element according to claim 1, characterized in that the ceramic block is made in the form of a cylinder with honeycomb cells coiled in a spiral and a hole along the axis.  3. A method of manufacturing a filter element containing the operation of forming a layer, drying, sealing, drying and firing, characterized in that the molding is performed in conjunction with a mesh of burnt material, which is burned during firing, then the channels are washed with liquid under pressure.

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