DEVICE FOR CLEANING HOT GASES FROM COMBUSTION ENGINES

Abstract: Arrangement for purification of hot exhaust gases from internal combustion engines and comprising a housing provided with a gas inlet (6) and a gas outlet (7) for the flow of gases through the inside of the housing, and a gas purification unit arranged in the housing between the gas inlet and the gas outlet. Between the peripheral casing wall (20) of the purification unit (16) and the wall of the housing there is a closed, gas-tight element (23) which extends peripherally round the purification unit and through the heat-insulating layer and is designed as a three-dimensional shell with an inner attachment (26) on the casing wall of the purification unit and an outer attachment (25) on the wall (8, 9) of the housing. The inner attachment is situated at a level which is nearer the outlet side of the purification unit than the level of the outer attachment. In this way the gas-tight element with its inner and outer attachments forms a gas-tight securing arrangement for the purification unit in the housing with minimal heat losses.

Description: Title : Device for cleaning hot gases from combustion engines Technical Field: The present invention relates to an arrangement for purification of hot exhaust gases from internal combus¬ tion engines and comprising a housing provided with a gas inlet and a gas outlet for the flow of gases through the inside of the housing, and a gas purification unit which is arranged in the housing between the gas inlet and the gas outlet and through which the gases are caused to pass, and in addition the purification unit has an inlet side open towards the inlet and an outlet side open towards the outlet and having a lower temperature than the inlet side, and a peripheral casing wall extending between the inlet side and the outlet side and positioned with an intermediate space between it and the wall of the housing, which intermediate space has a heat-insulating layer. Prior Art: A purification arrangement of the known type in the introduction is disclosed by SE 8400084-3. This arrange- ment comprises a filter unit which is fixed in a filter housing above an inlet chamber. The filter housing is lined with heat insulation and the fixing of the filter unit in the housing is achieved by casting the unit in fireproof cement. Cement casting on large-scale produc- tion is in this context an inefficient technique and involves, particularly in the case of mobile units, a risk of the filter unit being vibrated loose from its position. Even in the case of stationary units, high demands are placed on the fixing of the filter unit as a result of the vibrations generated by an internal combus¬ tion engine. In addition, special measures are required in order to obtain gas sealing via the insulation between inlet and outlet. Technical Problem: The aim of the present invention is to eliminate the disadvantages of the prior art in the attachment of purification units and to provide a simple, reliable solution with a gas-tight fixing of the filter unit, in which the heat losses to the environment are kept to a low level. Solution: The said aim is achieved by means of the arrangement according to the present invention, which is charac¬ terized in that there is arranged, between the peripheral casing wall of the purification unit and the wall of the housing, a closed, gas-tight element which extends peripherally round the purification unit and through the heat-insulating layer and is designed as a three- dimensional shell with an inner attachment on the casing wall of the purification unit and an outer attachment on the wall of the housing, in that the inner attachment is situated at a level which is nearer the outlet side of the purification unit than the level of the outer attach¬ ment, in that the said inner and outer attacrαnents form gas-tight, fixed connections between the said shell and the casing wall of the purification unit and the wall of the housing, respectively, at essentially different levels between the inlet side and the outlet side, as a result of which the said gas-tight element with its inner and outer attachments forms a gas-tight securing arrange¬ ment for the purification unit in the housing. Description of Figures: The invention will be described in greater detail below on the basis of an exemplary embodiment and with reference to the attached drawings, in which Figs. 1 and 2 show side views of the purification arrangement accord- ing to the invention, Fig. 3 shows a vertical section through the purification arrangement along the line A-A in Fig. 2, Fig. 4 shows a corresponding section through a part of the purification arrangement, and Fig. 5 shows a partially broken plan view of the said part shown in Fig. 4. Preferred Embodiment: As can be seen in Figs. 1 and 2, the purification arrangement according to the invention is provided with a filter housing 1 which is divided up into two housing halves 2, 3 each provided with its own laterally directed pJ-P e socket 4, 5, of which the lower one forms an inlet channel 6 and the upper one constitutes an outlet channel 7, see also Fig. 3. The filter housing 1 is essentially cylindrical with a cylindrical casing wall divided into two casing wall sections 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 with the lower casing wall section 8 and is positioned near the lower end wall 10, while the outlet pipe socket 5 connects with the upper casing wall section 9 near the upper end wall 11. Both the pipe sockets connect radially with the vertical central axis 14 of the housing from any chosen directions, in the example shown from diametrically opposite directions. This construction makes it possible for the gas stream, which in the running state is fed in through the inlet channel 6 and is fed out through the outlet channel 7, to pass through thfe'inside of the housing essentially in a direction from the bottom and upwards in the case of normal assembly with the said central axis directed vertically. Moreover, the two housing halves 2, 3 can be made similar in terms of their basic form and dimensions and the pipe sockets and their positioning. Furthermore, the two housing halves 2, 3 each have identical circular securing flanges 12, 13 which are directed peripherally outwards and are positioned symmetrically relative to the said central axis 14 and divide the halves relative to a horizontal dividing plane, in the example shown a mid-plane, close to the latter. The securing flanges 12, 13 form a connection part for the housing halves and have, in the example shown, a number of holes situated in line with each other for a screw connection or rivet connection in the form of screws driven through the holes and threaded in the one flange or alternatively secured by means of nuts, or else in the form of rivets, by means of which the housing halves 2, 3 are connected to each other. The section in Fig. 3 shows the construction of the inside of the arrangement. The housing 1 is provided on the inside with a layer 15 of heat-resistant heat insula¬ tion. Arranged in the filter housing is a purification unit in the form of a filter insert 16 with a downward- directed inlet side 17 and an upward-directed outlet side 18. The filter insert 16 has an essentially cylindrical part 19 with a closed cylindrical casing wall 20 and openings towards the inlet side and outlet side. Between the cylindrical part and the end walls of the housing, before their insulation layer, there are inlet and outlet chambers 21, 22 to which the inlet and outle- channels connect, respectively. The inlet chamber 1 and the outlet chamber 22 have an internal lining in ~ he form of a wall of, for example, sheet metal, separa a for each chamber, each of which via its annular sealing connects fibre-tight with the casing wall 20 of the filter insert 16 at its lower or upper annular edge section, respec¬ tively. Therefore, no internal lining in one single piece is required. According to the invention, the filter insert is provided with a securing arrangement 23 which extends round the cylindrical filter part and is designed as a three- dimensional gas-tight shell with an inner gas-tight attachment on the casing wall 20 of the filter insert 16 and an outer gas-tight attachment on the filter housing 1. The securing arrangement has a section 24, in the example shown designed as the outer surface of a trun¬ cated cone, which merges peripherally outwards into a plane flange section 25 which extends in a radial plane and projects in between the two flanges of the housing halves 2, 3. For attachment in the cylindrical filter part, the conical section 24 merges, in the example shown, into a cylindrical section 26 which connects with the outer surface of the cylindrical part and is, for example, welded onto this. The plane flange section 25 is arranged securely on the housing halves by means of the fact that the flange section has holes 40 (see Figs. 4 and 5) situated in line with the holes in the two secur- ing flanges 12, 13 of the housing halves in such a way that the securing arrangement is secured on the housing by means of the connection which secures the housing halves to each other. In the example shown, screws or rivets are thus driven through the holes in the plane flange section 25 of the securing arrangement and clamp it securely between the securing flanges 12, 13 of the housing halves. Annular seals 41 provide for sealing of the housing 1 with respect to the environment. The securing arrangement thus extends through the insulating layer, which here is divided along a corresponding conical surface. In this way the securing arrangement additionally forms a gas-tight separating wall between the inlet chamber and outlet chamber of the filter housing, as a result of which additional sealing between the filter insert and the filter housing does not need to be of a gas-tight type. As a result of the conical shape of the securing arrangement, the inevitable heat bricfge is long in relation to the thickness of the insulating layer, which keeps the heat losses to a low level. The conical shape moreover affords very favourable strength conditions and results in a very stable and secure suspension of the filter insert even in the case of a relatively thin plate in the cone section. Thin plate moreover contributes to reducing the heat losses to the environment. The securing arrangement 23 is thus fixed on the filter insert at a level, viewed between the inlet side 17 and outlet side 18, which essentially differs from the level at which the securing arrangement is fixed on the filter housing 1. In the example shown, the levels are chosen in such a way that the inner attachment, that is to say the one on the filter insert 16, is situated at a level which is nearer the outlet side, that is to say the colder end of the filter, than the outer attachment, that is to say the one on the housing. This additionally contributes to reducing the heat losses to the environment. Figs. 4 and 5 show the filter insert separately, from which it can be seen that the section 29 of the insulating layer which is situated outside the cylindri¬ cal surface of the insert and below the conical section can advantageously be secured on and integrated with the filter insert. The filter insert may additionally be of the conventional type. When using the arrangement for purification of exhaust gases from a diesel engine, the filter insert can be provided with a catalytic surface covering. The purification arrangement shown by way of example is moreover provided with an arrangement for regenerating the filter insert by means of burning the covering of particles in the filter by means of heating. As can be seen in Fig. 3, an electrical heating arrangement is therefore advantageously incorporated in the form of a heating element 40 situated at the inlet side 17 of the fiJT£er immediately below the filter insert 16. The heating element is designed as a helical loop laid in one plane and arranged with an intermediate space for passage of the gas stream. Moreover, a pierced reflector 28 is arranged, for example, and reflects and directs the heat radiation towards the inlet side of the filter insert. This too is therefore open in such a way that the gas stream can pass from the inlet channel and through the filter insert. The invention is not limited to the exemplary embodiment described above and shown in the drawings, but instead can be varied within the scope of the following patent claims. For example, the arrangement can in principle have a cross-sectional form other than a circular one, for example a polygonal form, from three corners up to a large number of corners. In this case the conical flange section is replaced by a number of plane surfaces which diverge in the direction downwards from the central axis of symmetry of the arrangement. The linear shape of the section 24 in cross-section can be replaced by any other suitable shape which affords the difference in level between the inner and outer attachments and retains the satisfactory strength characteristics. Moreover, it is conceivable for the housing not to be divided in its casing surface, in which respect the outer attachment of the securing arrangement connects with the housing in another way. It is also conceivable for the two housing halves not to be completely identical and, for example, to have different heights so that the flange sections do not end up near the mid-line of the arrangement. It is also conceivable for the housing to be divided into more than two parts and, for example, to have a cylindrical middle with an upper and lower flange section in each case forming a dividing plane. Instead of arranging a heating arrangement for regeneration, the filter insert can be regenerated outside the filter housing or alterna¬ tively can be completely replaced by a new filter insert. The purification arrangement can be of another type for purification of gases, for example a pure catalysing arrangement where the gas stream is caused to pass the catalysing element without special filtering.

Claims: Patent Claims 1. Arrangement for purification of 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 inside of the housing, and a gas purification unit (16) which is arranged in the housing between the gas inlet and the gas outlet and through which the gases are caused to pass, and in addition the purification unit has an inlet side (17) open towards the inlet and an outlet side (18) open towards the outlet and having a lower temperature than the inlet side, and also a peripheral casing wall (20) extending between the inlet side and the outlet side and positioned with an intermediate space between it and the wall of the housing, which intermediate space has a heat- insulating layer (15), characterized in that there is arranged, between the peripheral casing wall (20) of the purification unit (16) and the wall of the housing, a closed, gas-tight element (23) which extends peripherally round the purification unit and through the heat-insulat¬ ing layer and is designed as a three-dimensional shell with an inner attachment (26) on the casing wall of the purification unit and an outer attachment (25) on the wall (8, 9) of the housing, in that the inner attachment (26) is situated at a level which is nearer the outlet side (18) of the purification unit (16) than the level of the outer attachment (25), in that the said inner and ou€er attachments (26, 25) form gas-tight, fixed connec¬ tions between the said shell and the casing wall of the purification unit and the wall of the housing, respec¬ tively, at essentially different levels between the inlet side (17) and the outlet side (18), as a result of which the said gas-tight element with its inner and outer attachments forms a gas-tight securing arrangement for the purification unit in the housing. 2. Arrangement according to Patent Claim 1, charac¬ terized in that the housing (1) is divided into at least two parts (2, 3) and in that the said outer attachment connects to a dividing plane for at least two of the C! parts of the housing. 3. Arrangement according to Patent Claim 2, charac¬ terized in that the said dividing plane divides the housing (1) symmetrically. 4. Arrangement according to Patent Claim 1, charac¬ terized in that the said gas-tight element (23) has a section (24) which has the shape of a truncated cone. 5. Arrangement according to Patent Claim 2, charac¬ terized in that the said two parts (2, 3) of the housing (1) each have circular securing flanges (12, 13) which are connected to each other at the said dividing plane, and in that the said outer attachment (25) is formed by a flange section which projects in between the securing flanges of the housing parts and is secured between them. 6. Arrangement according to Patent Claim 1, charac¬ terized in that the said inner attachment (26) is formed by a flange section which connects with the casing wall (20) of the purification unit and has a shape correspond¬ ing to its periphery.

Inventors: BOERJESSON KJELL, EISMARK JAN, KLIPPARE STEN, LANDAELV HENRIK, BOERJESSON, KJELL, EISMARK, JAN, KLIPPARE, STEN, LANDAELV, HENRIK
Applicants: VOLVO AB, AB VOLVO
Application year: 1990
Main classification: F01N3
IPC codes: F01N3, F01N7