SE467702B - DEVICE FOR PURIFICATION OF HOT EXHAUST GAS FROM COMBUSTION ENGINE - Google Patents

Description

467 702 2 4, 5, of which the lower one forms an inlet duct 6, and the upper one consists of an outlet duct 7, see also Fig. 3. The filter housing 1 is substantially cylindrical with a cylindrical jacket wall, divided into two jacket wall portions 8, 9, and two end walls 10, 11, which are slightly convex and have a circular outer contour in the example shown. The inlet pipe socket 4 connects to the lower jacket wall portion 8 and is located near the lower end wall 10, while the outlet pipe socket 5 connects to the upper jacket wall portion 9, near the upper end wall 11. Both pipe sockets connect radially to the vertical center axis 14 of the housing the example diametrically opposite directions. Through this construction it is achieved that the gas flow which in operating condition is fed through the inlet duct 6 and discharged through the outlet duct 7 passes through the interior of the housing in the main roof in the direction from below and up during normal assembly with said center axis directed vertically. Furthermore, the two housing halves 2, 3 can be made the same with respect to their main shape and dimensions as well as to the pipe fittings and their location. The two housing halves 2, 3 further have their identical, circumferential, circumferentially outwardly directed mounting flange 12, 13, which are placed symmetrically relative to said center axis 14 and divide the halves relative to a horizontal dividing plane, in the example shown a central plane, in close proximity thereto . The fastening flanges 12, 13 form a connecting portion for the housing halves and in the example shown have a plurality of opposite holes for a screw joint or rivet joint in the form of screws passed through the holes and threaded in one flange or alternatively fastened by means of nuts and in the form of rivets whereby the house halves 2, 3 are connected to each other.

The section in Fig. 3 shows the construction of the interior of the device. The housing 1 is internally provided with a layer 15 of heat-resistant thermal insulation. Arranged in the filter housing is a cleaning unit in the form of a filter insert 16 with a downwardly facing inlet side 17 and an upwardly facing outlet side 18. The filter insert 17 has a substantially cylindrical part 19 with a closed cylindrical jacket wall 20 and openings towards the inlet and 3 467 792 outlet side. Between the cylindrical part and the end walls of the housing, inside their insulating layer, are located an inlet and an outlet chamber 21, 22, to which the inlet and outlet ducts connect, respectively. The inlet chamber 21 and the outlet chamber 22 have an inner cladding in the form of a wall separate from each chamber of, for example, sheet metal, which via each annular seal connects the fiber wall 20 of the filter insert 16 to its lower and upper annular edge portion, respectively.

Thus, no inner lining in a single piece is required.

According to the invention, the filter insert is provided with a holding device 23 extending around the cylindrical filter part, designed as a three-dimensional gas-tight shell with an inner gas-tight attachment in the jacket wall 20 of the filter insert 16 and an outer gas-tight attachment in the filter housing 1. The holding device has a portion 24, i the example shown is designed as the mantle surface of a truncated cone, which peripherally outwards merges into a flat flange portion 25, which extends in a radial plane and projects between the two flanges of the housing halves 2, 3. For attachment to the cylindrical filter part, the conical portion 24 in the example shown merges into a cylindrical portion 26, which connects to the outer surface of the cylindrical part and is welded to it, for example. The flat flange portion 25 is fixedly attached to the housing halves by the flange portion having holes 27 (see Figs. 4 and 5) located in the middle of the holes in the two mounting flanges 12, 13 of the housing halves so that the holding device is held to the housing by the joint holding the housing halves together. In the example shown, screws or rivets are thus passed through the holes in the flat flange portion 25 of the holding device and clamp it. between the mounting flanges 12, 13 of the housing halves. Annular seals 28 ensure sealing of the housing 1 against the surroundings. The holding device thus extends through the insulating layer which is here divided along a corresponding conical surface. In this way, the holding device also forms a gas-tight partition wall between the inlet chamber and the outlet chamber of the filter housing, whereby other seals between the filter insert and the filter housing do not have to be of the gas-tight type. Due to the conical shape of the attachment, the inevitable heating bridge becomes long in relation to the thickness of the insulating layer, which keeps the heat losses at a low level. The conical shape also provides very favorable power conditions and results in a very stable and fixed suspension of the filter insert even at a relatively thin plate thickness: in the cone portion. Thin sheet thickness further contributes to reducing heat losses to the environment.

The holding device 23 is thus attached to the filter insert at a level, viewed between the inlet and outlet sides 17, 18, which differs substantially from the level at which the holding device is attached to the filter housing 1. In the example shown, the levels are so selected. that the inner attachment, i.e. the one in the filter insert 16, is located at a level which is closer to the outlet side, i.e. the colder end of the filter, compared to the outer attachment, i.e. the one in the housing. This further contributes to reducing heat losses to the environment.

Figs. 4 and 5 show the filter insert separately, it being seen that the portion 29 of the insulating layer which is located outside the cylinder shell surface of the insert and below the conical portion can advantageously be attached to and integrated with the filter insert. The filter insert can otherwise be of a conventional type.

When using the device for purifying exhaust gases from a diesel engine, the filter insert can be provided with a catalytic coating.

The purification device shown as an example is further provided with a device for regenerating the filter insert by heating the coating of particles in the filter by heating. As can be seen from Fig. 3, therefore, an electric heating device in the form of a heating element 27 is advantageously located located on the inlet side 17 of the filter immediately below the filter insert 16. The heating element is designed as a helical loop laid in a plane and arranged at intervals to allow gas flow. . Furthermore, for example, a perforated reflector 28 is provided which reflects and directs the heat radiation towards the inlet side of the filter insert. This is also so open that the gas flow can pass from the inlet duct and through the filter insert.

The invention is not limited to the embodiments described above and shown in the drawings, but can be varied within the scope of the appended claims. For example, in principle the device can have a non-circular cross-sectional shape, for example a polygonal shape, from a triangular up to a polygonal shape. In this case, the conical flange portion is replaced by a plurality of flat surfaces, which diverge in the downward direction from the central axis of symmetry of the device. The linear shape. of the portion 24 in the cross-section can be replaced by any other suitable shape which provides a level difference between inner and outer attachment while maintaining satisfactory strength properties. Furthermore, it is conceivable that. the housing is not divided in its mantle surface, the outer attachment of the holding device connecting to the housing in another way. It is also conceivable that the two housing halves are not completely identical and, for example, have different heights, so that the flange portions do not end up close to the center line of the device. It is also conceivable that the housing is divided into more than two parts and, for example, has a cylindrical waist with an upper and a lower flange portion which each form a dividing plane. Instead of arranging a heating device for regeneration, the filter insert can be regenerated outside the filter housing or alternatively be completely replaceable to a new filter insert. The purification device can be of another type for purification of gases, for example a pure catalyst device, where the gas stream is caused to pass through catalyst elements without special filtration.

Claims (6)

10 15 20 25 30 35 467 7Û2 6 Patent claim Device for purifying hot exhaust gases from internal combustion engines and comprising a housing (1), provided with a gas inlet (6) and a gas outlet (7) for the flow of gases through the interior of the housing and one in the housing between the gas inlet and the gas outlet arranged gas purification unit (16), which the gases are passed, and the purification unit has an inlet side (17) open to the inlet and an outlet side (18) open to the outlet, which has a lower temperature than the inlet side and one between the inlet side and the outlet side extending peripheral jacket wall (20), placed at intervals to the wall of the housing, which gap has a heat-insulating layer (15), may be characterized in that between the peripheral jacket wall (20) of the treatment unit (16) and the wall of the housing is arranged peripherally around the purification unit and through the heat-insulating layer extending, closed, gas-tight element (23), which is designed as a three-dimensional shell with a peripheral inner attachment (26) at the jacket wall of the treatment unit and a peripheral outer attachment (25) to the wall (8, 9) of the housing, that the inner attachment (26) is located at a level which is closer to the outlet side (18) of the treatment unit (16) than the level of the outer attachment (25), that said inner and outer attachments (26, 25) form gas-tight, fixed connections between said shell and the jacket wall of the purification unit and the wall of the housing, respectively, at substantially different levels between the inlet side (17) and the outlet side (18), whereby said gas-tight element with its inner and outer attachment forms a gas-tight holding device for the cleaning unit in the housing. w 10 15 20 25 467 782 7 Device according to claim 1, characterized in that the housing (1) is divided into at least two parts (2, 3) and that said outer attachment connects to a dividing plane for at least two of the parts of the housing. Device according to claim 2, characterized in that said dividing plane divides the housing (1) symmetrically. Device according to claim 1, characterized in that said gas-tight element (23) has a portion (24) which forms the shape of a truncated cone. 5. Device according to claim 2, characterized in that said two parts (2, 3) of the housing (1) each have their own circumferential mounting flange (12, 13), which are connected to each other at said dividing plan, and that said outer attachment (25) is formed by a flange portion which projects between the mounting flanges of the housing parts and is held between them. Device according to claim 1, characterized in that said inner attachment (26) is formed by a flange portion which connects to the jacket wall (20) of the purification unit and has a shape corresponding to its circumference.